The ability to use old save data (or in rare cases, use of the physical game) from an old game in a new game (often a direct sequel, though unrelated examples aren't unheard of) for a bonus. Mostly, this means a tiny change (such as an acknowledgment of your accomplishments in the first game), or an item that may or may not be useful, but in some RPGs (the main originators of this trope) it is possible to import the character from the last game, levels intact, to start the new one (the monsters would sometime be scaled up, of course).
Sometimes, this is a way of avoiding the Bag of Spilling problem. Mission Pack Sequel games are especially prone to using this, as the sequel is usually built on the same basic code as the previous entry, so it's easy to port over content.
Related is the specific bonuses achieved from linking a handheld with a specific game to a console with another. This began with the Nintendo 64 title Pokemon Stadium, which has a special adapter for importing Game Boy save data. The Game Boy Advance system has a link cable for connecting to the Nintendo GameCube, the Nintendo DS uses its Slot-2 to connect to GBA games and can connect wirelessly to the Wii, and the PlayStation Portable uses a USB cable to connect to the PlayStation 2. However, this can quickly enter One Game for the Price of Two territory.
Compare to New Game+ and Another Side, Another Story, which reward you for playing the same game again after completing it once.
Unlocking Japanese as an audio option for Theater Mode instead of the default English in Kingdom Hearts II: Final Mix+ requires having a finished Re: Chain of Memories save file on the memory card. Notably, Final Mix+ added a few cutscenes not in the original edition of the game, which means that there is no English voiceover available for them. This, in turn, means that these cutscenes are essentially muted until you get around to finishing the other game. Which, naturally, is entirely in Japanese. At least Re: Chain of Memoriescomes withFinal Mix +...
Though this trope was dead for many years, it's not really all that new on computers: in early installments of Ultima, Bard's Tale or Wizardry, it's possible to import a player from each game in the same series into the next game - although this ended at least a decade before the release of Ultima IX.
The ultimate example is Sierra's Quest for Glory. Every game in the series after the first allows importing earlier characters, meaning that if you played your cards right you could start each game significantly stronger than a brand-new character, and with a ton of cash to boot. In Quest for Glory II, a player who's conducted the entire game virtuously and gone well out of his way and against common game mechanics (for instance, returning a reward) to do so will have his character receive a Flaming Sword and the hidden "Paladin" class as the last scene of the ending; both are only usable in the sequels. Fittingly enough, the Paladin's hat is selfless good. Since it could very easily be Lost Forever, Quest for Glory III features a Paladin quest that only takes up half the game, while Quest for Glory IV lets one change an imported character due to a bug in reading the old save files.
This trope resulted in the quirk of a game that in itself does not favour a gender having a Game-Favored Gender: in the first two Bard's Tale games, the gender of the adventurers was not selectable, and they were all male. In the third, females were an option, and equal to creating a male character... but since they hadn't been in the earlier games female characters couldn't get any of the very useful old save boni.
The Wizardry series of video games let you do this in the second, third, and fifth games by letting you import characters from previous games (except the fourth, which was a standalone adventure) to make descendants as playable characters. These had greatly lowered stats, and were at level one. However, they kept the same job as their parents, letting you start out with the advanced classes.
Wizardry VIII, the last game of the series, pushed the envelope by having you not only keep your character, but some of the allies and affiliations they had made in the previous game. This changed your starting location to your ally's base, and severely altered the way in which you could resolve the plot... assuming, that is, you were one of the few who still had their Wizardry VII saves from nine years ago!
The somewhat obscure Roguelike for Windows 3.x, Castle of the Winds, came in two parts. The Shareware first part allowed you to save your game after beating the Big Bad of the game, where you could then continue it in the commercial second part exactly as left. This created a bit of a problem for characters created anew in the second part, since it was tuned for an already-leveled and geared character. It got around this by giving new characters some instant levels and gear, although characters brought forward from the first part were typically significantly better off.
Both Neverwinter Nights games allow you to save your characters and load them into the expansion packs and free content modules so that you can continue their adventures over multiple stories.
In the first game, you could do this to great benefit, quickly collecting some magical gear and starting the game much better equipped than usually.
Baldurs Gate II allowed you to import player characters from the first game. Barring an exploit, you lost most of your equipment, but you could start at a higher level this way if you installed the expansion pack and made it to the (increased) level cap from the first game. In addition, some of your equipment from the last game would turn up in-game. This included the golden pantaloons, an item that could be combined with the silver pantaloons from the second game and the bronze pantalettes from Throne of Bhaal to make a very powerful suit of armor and accompanying weapon.
Going from Baldur's Gate II to the Throne of Bhaal expansion, it was much better to start the expansion by replaying the last battle of the game and going straight through to the expansion as opposed to creating a new character or even importing your character from the last game.
With the semi-official Ascension mod installed, if the player picks up the Sword of Chaos from Irenicus' dungeon in Chapter 1, holds onto it for the entirety of the game and has it on them when importing into Throne of Bhaal, then chooses to recruit Sarevok, the former villain will (via a special conversation) recognize his old sword and give it a power boost, turning it into a much deadlier weapon.
The popular Baldur's Gate Tutu and Baldur's Gate Trilogy mods allow you to combine the original Baldur's Gate and it's expansions with Baldur's Gate II and the Throne of Bhaal expansion, forming a single massive game played on the BGII engine. There are even extra bits of cutscene dialogue in order to smoothly transition from one game to the next. As somebody once explained, "Somebody made a mod for BGII; the plot is that of BGI."
Originally, Neverwinter Nights was intended to be compatible with character files imported from the BG games. As it spent five years in Development Hell, and was ultimately released using 3E rules rather than 2E AD&D rules, however, this became impossible, and was left out of the final release.
The Ratchet & Clank sequel Going Commando rewards players of the previous game with the five returning weapons being sold for free if you have bought them in the first game beforehand. The third game, Up Your Arsenal, does it for the two previous games seperately, with price discounts from a Ratchet & Clank save and the five returning Going Commando weapons for free if you have upgraded them to Mega in that game. This is because the player is told by the Gadgetron head after a certain quest of the first game that the player is entitled to the employee discount in two years time. The second game takes place in a different galaxy with a different main corporation you buy things from. The third game returns to the galaxy in the first game; these games are developed at a rate of one a year, so the third game was released almost exactly two years from the time the first game was... turns out the man's true to his words.
The FutureStory Arc does it too: While Quest for Booty doesn't get anything unlocked from Tools of Destruction, A Crack in Time gets seperate bonuses from both predecessors (Price discounts from Tools of Destruction and a wearable pirate hat for Ratchet from Quest for Booty).
Silent Hill 3 has an Easter Egg only available if you have a Silent Hill 2 save file on your memory card. Examine a toilet in one of the mall's bathrooms, and the game will say there's something stuck in here, then ask if you want to retrieve it. If you say "yes", Heather will try to get whatever is stuck here, but will eventually gross out and refuse to do it. This is a Shout-Out to Silent Hill 2, where you must retrieve a safe box combination from a wallet stuck in a toilet.
You can find a few other easter eggs if you examine the mailboxes in Woodside Apartments, inspect the fencing on the roof of Brookhaven, and look around Heaven's Night.
We Love Katamari, the sequel to Katamari Damacy, can import the star data created in the previous game into the new cosmos map.
In the PSP game Metal Gear Solid: Portable Ops, having a save from the two Acid games and the Digital Graphic Novel unlocks Teliko, Venus and Zero respectively for the second playthrough.
If you have a saved file of Sakura Wars 1 on your PS2 memory card, it will allow you to unlock otherwise un-playable levels and secrets when you play Sakura Wars 3 and Sakura Wars 5 Episode 0 with the same memory card. The Dreamcast version of Sakura Wars 3 also opened up new dialogue options if you had a save from the first two games.
"Stop 'n' Swop" in Banjo-Kazooie and Banjo-Tooie was meant to be a rare cartridge-based form of this, whereby you could swap the two games over during play, taking items from one game to another to unlock secret bonuses. Changes to the Nintendo 64 prevented the idea from being fully realized until the Xbox LIVE Arcade remakes, where Stop 'n' Swop also unlocks additional content in Nuts & Bolts. Doing Stop 'n' Swop between the Xbox LIVE Arcade versions of Banjo-Kazooie and Banjo-Tooie will give you three new bonuses in Tooie on top of the original four: a Gamer Pic, a Banjo-Kazooie Theme, and Stop 'n' Swop II, which apparently involves three new eggs.
Jak X Combat Racing for PS2 and Daxter for the PSP mutually unlock game features for both games when linked via the PS2 USB port.
In the four-part Sorcery!gamebook series (part of the Fighting Fantasy series), you can carry over all your equipment and stat modifications from one book to another. The benefits range from minor shortcuts to vital hints to allowing you to skip particularly annoying Luck Based Missions.
It is very well advised to Play the Lone WolfGamebook series right from Book 1 to the end and ESPECIALLY Book 2 for a super-powerful magic sword called the "Sommerswerd" if you don't want hair-rippingly frustrating and frequent "instant death" entries from Book 3 on. Though a couple of battles are actually easier without the Sommerswerd.
On Mario Kart Wii, having a save game from Super Mario Galaxy and then playing 50 races is the easier method for unlocking Rosalina as a playable character.
F-Zero GX actually allows the sharing of data between itself and the Arcade GameF-Zero AX. As AX machines are hard to find in the US (at the height of their popularity there were a grand total of 20 of them available to the English-speaking world) and few people read the back of the box, hardly anyone ever noticed. The AX version did contain a semi-exclusive cup, which could be unlocked in GX if you beat the courses in AX with a GC memory card inserted to the machine; but because of the rarity of the AX machines, the only way to unlock this AX cup that most players have access to is to beat every cup on Master difficulty.
This becomes slightly less hard to do when it was discovered that AX is actually contained withinGX!
The original .hackseries of games is a serial game, one game in four parts. You're really encouraged to finish the prior game before going on to the next game in the series, as the monsters are very strong for a first-level character. You keep all of your items, equipment, money, levels, etc. if you have a completed save from the prior game, as it is supposed to be taken as a single large game. Fortunately, if you do start your game fresh, you'll be started at a reasonable level (30 for part 2, 50 for part 3, 70 for part 4) with generic level-appropriate equipment, so you're not totally screwed for not having played the previous games, though certain things may be unavailable if not imported. The sequel, .hack//G.U., is a set of three games that works the same way.
.hack//G.U. also names one character after your main character in the original games, if you import as save file from any of the original 4 games, and gives you a secret Email. You get second secret email if you import from the original game's fourth volume. The other three only give you one.
Assassin's Creed IV: Black Flag gives Edward the outfits of the protagonists of the previous entries in the series for having data of the games on your Uplay account (so it's unlocked even if you're on another platform).
Most EA Sports titles reward players for playing earlier versions of the game, specifically versions from the previous year.
The College Football players you create in recent edition EA's NCAA Football series can have pro careers by being imported to your copy of corresponding editions of the Madden NFL series. If you also owned NFL Head Coach 09, you could use its advanced play editor to import custom plays into Madden 09.
There are simply tons of Nintendo DS games that have small bonuses when you put an appropiate GBA game into the GBA slot.
Putting a Sega game in the GBA slot while playing Project Rub/Feel the Magic XY/XX on DS unlocked special hats for the girl. The same items can be unlocked without the GBA games, but it takes a lot longer.
Putting one of the GBA Kim Possible games into the GBA slot when playing the DS game Kimmunicator would unlock one of three bonus outfits for the title character, one for each title.
Placing a WarioWare: Twisted! cartridge in the GBA slot of your Nintendo DS while playing WarioWare: Touched! will unlock the Mona Pizza music video. North American gamers probably didn't know about this Easter Egg at first, because Touched! was released before Twisted! in the States (in Japan, the reverse is true).
And even if you do get a copy of Twisted!, it won't work with an European Touched! copy anyway.
Having Advance Wars 1 or 2 in the DS and starting Advance Wars: Dual Strike would unlock certain items to be purchased in-game.
Also, in Castlevania: Dawn of Sorrow, if you start with Castlevania: Aria of Sorrow you can get a Rare Ring for free at the start. There's also a cute Mina doll in the background of Yoko's shop that's only there if Aria of Sorrow is in the GBA slot.
If you played Harvest Moon DS with Harvest Moon: Friends of Mineral Town in the GBA slot, the inhabitants of Mineral Town would visit Forget-Me-Not Valley periodically. You could even date and marry some of them, though the game would end the moment you married them. Going even further, if that particular copy of Friends of Mineral Town had linked up with a copy of Harvest Moon: A Wonderful Life, then a tombstone for that game's character will appear in game.
Putting Mega Man Zero 3 or 4 in the GBA slot when playing Mega Man ZX allows you unlock a door that lets you fight the bosses from said games.
Putting any GBA Mega Man Battle Network game in Slot 2 while playing Battle Network 5 DS would net you bonuses in-game. A Boktai or Boktai 2 cartridge would also net bonuses; 2 (3 in Japan) netting MegaMan the overpowered Sol Cross.
Also, if you had a GBA copy of BN5 in Slot 2 that had the Bass/Forte icon on the title screen (acquired by beating said boss not once, but twice, and he's stronger the second time), you could access Bass Cross, with different bonuses in that form depending on which version-half of BN5DS you were playing.
Not Just Bass/Forte Cross. You could import your old folder from the GBA version to the DS version - the only restriction being you have to be able to equip it as you are (which, if you're using Sol or Bass Cross, you most likely can't, due to -1 Mega Chip). Importing a folder made for the endgame at the start of the new one makes it so easy it's almost funny.
Also, oddly enough, the bonus for the Japan-only 4.5 game exists in non-Japanese versions of 5.
Putting a Mega Man Battle Network game in Slot 2 while playing the first Mega Man Star Force would unlock a mini-quest that got you the BN Buster, which was quite a good weapon for the entirety of the game. A similarly unlockable sidequest in Mega Man Star Force 2 provides not only a new weapon but also an epilogue to the Battle Network series.
Playing Kirby Canvas Curse with another Kirby game in the GBA slot allows you to play as a Waddle Doo before unlocking it regularly (which is extremely late post-game).
Putting the Japan-only Ace Attorney GBA games into their corresponding DS remakes will unlock all cases from the start.
Super Robot Wars W and K both give you very good mech parts if you use one of the Japanese GBA cartridges in the Slot-2. And a very good part if you use the Game Boy Super Robot Wars 2 (part of the Famicom Mini collection).
Lunar Knights gives different bonuses for having the various Boktai games inserted in the GBA slot, in the form of reading the sunlight input. The Boktai games themselves have passwords at the end that can be used to carry over a character's rank.
Ganbare Goemon: Toukai Douchuu Ooedo Tengurigaeshi no Maki has several character cameos and a demo of Space Manbow that can be unlocked by putting Kessakusen! Ganbare Goemon 1+2 in the GBA slot.
Having Yggdra Union in the GBA slot while playing Knights in the Nightmare gives you the opportunity to recruit Pamela at a random point later in the game, and the tutorial will have Yggdra as its guide instead of Maria, with arranged music from Yggdra Union in the background.
In Monster Farm DS, one method of unlocking monsters is by inserting a game - any GBA game - into the GBA slot, and some formula works out what monster to make, but is still played straight as there are two special monsters that can only be unlocked with this feature, with the required games being the two GBA games of the Monster Farm franchise. (That is, the Japanese versions of those games. Monster Rancher is the English name of the franchise, and the English versions of the game do not give the special monsters.)
Pokémon Black and White have two ways to transfer Pokémon from previous versions: the normal way is a "Poké Transfer" minigame download to another system that has a Gen IV game in it available after getting the National Dex, while the "Relocator" is a secret method to move over a few specific Pokémon from promotional events that were held for the previous games just before the new games' release. It can be used as soon as you reach the city it is in.
A similar thing happened earlier, when Pokémon Gold and Silver allowed players who'd reached a certain point in the game to use a Time Capsule to trade with the earlier games in the series. In this case, you could only trade back Pokémon that existed in the old games and had moves from them. As in D/P, this was the only way to get several Pokémon.
Ordinarily, Pokémon games that are part of the same "generation" can trade with each other no matter when they were released, but FireRed and LeafGreen require you to complete a sidequest before trading with the Hoenn games is allowed.
Pokémon Black 2 and White 2 have the Memory Link function, which connects the game to a Pokémon Black and White save file and adds a few bonus cutscenes to the game as well as references by name to the previous game's protagonist. Also, in the companion game Pokémon Dream Radar, after catching Landorus, it's possible to unlock new search methods to get Dream World versions of Dialga, Palkia, Giratina, Ho-oh, and Lugia by inserting a copy of Diamond, Pearl, Platinum,Heart Gold, or Soul Silver (respectively) into the 3DS while starting the game. (These Pokemon are only available once per both each Dream Radar save and each save of Black 2 or White 2).
Star Ocean: Till the End of Time has a New Game+ version of this. A special, separate save is made at the beginning of the game for battle trophies. When the player collects a certain number of battle trophies, they will unlock new rewards. Since this file exists as a separate save, the player can take on a boss multiple times, first to get one trophy, then resetting the game after the battle and fighting the boss again for another. During subsequent playthroughs, the player is allowed to carry over their battle trophies.
The Sega Dreamcast version of Shenmue II allowed players to transfer collected items over from the first game. Unfortunately, the American version was never released, so the few U.S. gamers who imported the European version could only exploit this feature by hacking the Shenmue I save file to add the flags indicating it is a European save file (though the game does play fair by giving Ryo a few collections by default to sell for cash).
Tomba! 2 had several quests that could only be accessed by completing the first Tomba to a certain point and transferring the data over.
In Spyro 2: Ripto's Rage! starting a new game on the same memory card as an already 100% completed save grants the player with the use of the permanent superflame powerup at the start of the new game.
Shin Megami Tensei: Digital Devil Saga 2 had a ton of save bonuses if the player had completed the first game. Bonuses included improved starting stats, special abilities, anti-element rings (gained by defeating the Bonus Bosses in the first game), and even getting Heat back into your party.
While we're talking Mega Ten, there are also a few examples of this in the Persona series:
Most American gamers were unaware of the fact that Persona 2was a duology. If you completed Innocent Sin, you could transfer Tatsuya's stats to Eternal Punishment.
If you have an existing Persona 3 save when you load FES, you can transfer your attributes and Personae Compendium, effectively making FES a New Game+.
Predating all of these is Shin Megami Tensei If. Upon reaching the World of Sloth, having save data from other Atlus games would get the player a large number of bonuses; having all the correct saves can get the player 3 free points in strength, 5 in intelligence, and 10 in agility. While this may not sound like much on paper, in gameplay it's like getting 18 extra levels, leaving the player just shy of being able to max out every stat.
The Suikoden series of videogames uses this trope liberally. By importing save data from the first game with all 108 stars recruited, a lengthy bonus scenario involving two of the previous game's main characters would be available in Suikoden II. Likewise, data could be copied from Suikoden II to Suikoden III to unlock hidden plays (with further bonuses for copying a save from Suikoden II that had had its bonuses unlocked by the copying of data from the first Suikoden — and in Japan, yet further bonuses for routing a Suikoden II save through the two Suikogaidens and then into Suikoden III, but those games never came to the US), and between Suikoden IV and Suikoden Tactics to unlock two extra characters. Sadly, with the release of the fifth game in the series, this practice seems to have been discontinued.
This may be an issue of in-game timing rather than discontinuing what has always been a popular feature of the series. Data from Suikoden I could be used in II because the events in II happen shortly after I, and the same went for data from II being used in III. But because IV jumped back in time 150 years, it didn't accept load data from the earlier games... and V jumped back ahead to shortly before the first game, so it didn't accept load data either. Whether or not Suikoden VI will eventually accept data from earlier games likely depends on when it is set in the timeline - and on which system it is eventually released. Odds are you're not going see a Suikoden VI released on the 360 that somehow reads save files from the earlier PS1 and PS2 games.
LegoStar Wars 2 has an "extra" that allows the user to import characters from a Lego Star Wars (1) save file for use in the "Free Play" mode. Of course, this (and the two games themselves) was made obsolete with The Complete Saga.
Although it's an online game and thus has no 'save' option, Guild Wars uses a related mechanic. In Eye of the North, there is a Hall of Monuments that can store mementos of character's personal achievements. The developers have announced that it will be possible to obtain special bonuses for characters in Guild Wars 2, based on the contents of the Hall.
In Legend of Mana, one of the early quests introduces the player to the mechanics of catching monster eggs, which would eventually hatch into friendly monsters the player could bring along. The starter monster would always be a Rabite (a small, relatively weak rabbit monster) unless the player happened to have a save from Final Fantasy VIII on their memory card - in which case the monster would be a Chocobo. Also, having a Saga Frontier 2 save file allowed you to find a secret sword in Bone Fortress, and having a Chocobo Racing save net you a ring accessory from Polpota Harbor.
Golden Sun: The Lost Age gives players golden equipment if they send clear data from the first game to the second game if the player triggers certain events from the first game. Finding out through an NPC that the thieves from Vault escaped will appear in the second game and fight your party. A girl from one of the towns from the first game appears halfway through the second game to give Isaac a gift for helping her friend. The warriors from the Colosso appears late in the sequel once Isaac and his party joins your party and they fight you, accusing Isaac of cheating when they fought him.
There's also the fact that getting into the final Bonus Dungeon requires you to find all the games Mons - in both games.
The core element of the Mass Effect series is the ability to transfer saves from one game to the next (and drastically impact the plot and background events as a result):
Importing a save from Mass Effect 1 to Mass Effect 2 preserves all the decisions made in the first game: whether or not you saved/killed the Rachni Queen, the Council and Wrex, the Virmire survivor, etc. In fact, the sequel takes a decidedly different tone if you've imported a game (some conversations and dialogue actions will be different). Playing without importing a save gives you the worst possible start (a Shepard that is assumed to have taken all Renegade options and killed the Council/Wrex/the Rachni Queen).
If the Mass Effect: Galaxy mobile game is completed and its save data imported into Mass Effect 2, additional dialogue options will be available if both Jacob and Miranda are in the party during the Omega: Packages for Ish sidequest.
Mass Effect 3 carries over many of the player's plot choices from both games (including the Mass Effect: Genesis interactive comic for the PS3 version, the DLC-only character Zaeed Massani from the sequel and the "Arrival" downloadable mission, which leads directly into the third game). Depending on which characters lived or died, certain sidequests will have different dialogue/cutscenes or will be permanently inaccessible. And again, starting 3 from scratch leads to certain assumed decisions; apart from the defaults to 2, DLC squadmates were never recruited, virtually no loyalty missions were completed, Tali was exiled, and Grunt, Thane, Jack, Samara, Legion and virtually the entire Cerberus crew of the Normandy SR-2 are dead.
Likewise, the Citadel DLC carries over certain characters (like Wrex/Wreav), romance options and plot flags from the main game.
There is even a special Intel Bonus that is unlocked by importing a save from 2 where Kelly Chambers is alive and you bought the Prejak Paddlefish, completing that save for 3, then importing that save again. There is no hint whatsoever that this exists until you actually unlock it.
The various Arc The Lad sequels have bonus content and characters that can only be unlocked by save files from the previous games.
In Xenosaga, possessing Game Clear data from Episode I when starting Episode II gave your entire party the ability "Swimsuit", which dressed them up in swimsuits of various appeal, but more importantly boosted your Speed (And was one of the only ways to) and couldn't be obtained any other way. Game Clear data from Episode II to Episode III also unlocked a couple new costumes as well (Such as Shion's Vector uniform from I/II), which were again otherwise unobtainable. Both game's save data also allowed for a bonus in starting XP and skill points for characters in the next game, though the benefits were severely curtailed; maxed-out levels in the first game would add perhaps 4-5 levels to your starting total in the second.
SSI also made a Mini Game and Side Quest compilation, Hillsfar, in which you could import your Gold Box characters and play through a series of events which would give the characters increased experience, skill and valuables before you exported them to another adventure.
Though, if I remember correctly, none of the sequels actually let you keep your loot from the prior games - instead, each started with something happening to take away any equipment you might already have, such as being teleported thousands of miles away or being captured by the enemy.
This also happens quite a bit in tabletop D&D. It's not at all uncommon to dig up old, high level, characters for an epic campaign.
Panzer Dragoon Saga will give you extra money based on how long you've played Panzer Dragoon Zwei. You can also get a music box as a bonus item later in the game, and Saga will also unlock any bonus features in Zwei that haven't been unlocked yet.
Not quite the same, but Yu-Gi-Oh! GX Tag Force 2 let's you get three copies of a specific card when you use its UMD recognition system (think a handheld version of Monster Rancher's "monsters from CDs" gimmick). What makes this an Old Save Bonus is what you get when you first use it with the first Tag Force game: one each of the Egyptian God Cards, very much playable and legal in-game.
Yu-Gi-Oh! 5Ds Tag Force 4 takes it one step further... sort of. Using UMD recognition with each Tag Force Game will unlock the Effect Monster (i.e. versions of the cards that can be used IRL) version of each of the God Cards as well as a lot of rare cards (including anniversary edition versions of popular cards, like Dark Magician Girl). Tag Force 2 and 3 also unlock alternate versions of Akiza Izinski and Kalin Kessler, respectively for you to duel.
Using UMD Recognition in Tag Force 3 unlocks Bastion Misawa by having the game recognise Tag Force 2.
Burnout Revenge rewards Burnout 3 players with a borderline Game Breaker - the second most powerful crash car in the game unlocked right at the start. And if you had a Madden NFL 06 save game on your memory card, a special Madden van will be unlocked when you start up Burnout Revenge on PS2.
Gran Turismo 4 gave a 100,000 credit bonus to those who possessed a GT3 save file. Also a possible gamebreaker... considering that the majority of difficult races in the series are at the start, when it's tough to simply out drag race and bumper car the AI.
The PS2 edition of Samurai Warriors 2 lets you play as Hattori Hanzo and Uesugi Kenshin from the start if you have the save file from the first game, as well as letting you use Honda Tadakatsu for having save data from Samurai Warriors XL. Otherwise, they would need to be unlocked.
Having a save file from the Iron Man video game on your system unlocks Iron Man (in Hulkbuster armor) as a playable character in the Incredible Hulk video game.
The Naruto: Ultimate Ninja series of video games reward you for having save files from the previous games on your memory card, typically with in-game cash and (quite mysterious) ninja (info) cards.
If you have a GameCube memory card with Fire Emblem: Path of Radiance save data plugged into your Wii when you make a new game on Fire Emblem: Radiant Dawn, characters that were in both games (most of the cast) can have their stats improved. In theory anyway. A rather nasty bug in the North American version of Radiant Dawn, caused by the arbitrary renaming of difficulty settings in the localization, makes the game crash when this is attempted if there are any easy difficulty saves on the memory card.
Also, Path of Radiance had some bonus unlockables of its own that could be achieved by linking up with a GBA with Blazing Sword, Sacred Stones, or (Japanese version only) Sealed Sword inserted.
In order to hear a conversation between Soren and Ike in Fire Emblem: Radiant Dawn, you would need a save game file from Path of Radiance. The relationship level between both characters needs to be A in both games. There are other requirements but this is the main one.
Need for Speed: Most Wanted started you off with $30,000 to buy your first car, which basically meant a choice of three out of the four initially unlocked cars. If you were playing this game on a system that also saw the release of Need For Speed: Underground 2, if you had the save file for that game (all platforms) or at least installed it (PC), you get an extra $10,000 to start with, expanding your available starter choices to all four.
If you had the demo for Most Wanted on your PC or XBOX 360's hard drive, you would also unlock an extra performance marker.
The JauntTrooper games could be completed in order by a single character.
Animal Crossing: City Folk lets a player import a character from the predecessor Animal Crossing: Wild World. Only the name, face, hair, and catalog transfer; relationships, clothing, items, and money do not. The data on Wild World stays intact after this is done, so the data that isn't transferred isn't gone for good.
If it counts, Resetti will also thank you for buying both games during the first encounter, if you do transfer your character from Wild World to City Folk.
Unlocking three achievements in the first Gears of War game would unlock three multiplayer characters in Gears of War 2.
Ace Combat Zero: The Belkan War had a couple of these. If you had an Ace Combat 04 save on your memory card, you could unlock one of the superplanes, the X-02 Wyvern, from the very start of the game for $430,000. If you had an Ace Combat 5 save, you could unlock the ADF-01 FALKEN without having to get all three Supreme Ace medals (instead settling for the 3 Ace medals). However, if you had saves from both games, you unlocked both superfighters just by completing the first mission in the campaign.
A completed Tales of Symphonia save file nets you a reward in its sequel if you plug the Gamecube's memory card into your Wii. Said reward is random, ranging from small/cheap healing items that end up saving you some cash to experience boost items for monsters.
The Legend of Zelda: Oracle of Ages and The Legend of Zelda: Oracle of Seasons were meant to be played one after the other (in either order.) Data was transferred between the games by a generated password allowing you to fight Twinrova and rescue Zelda in the second game. There were also dozens of passwords you could get from NPCs to perform multi-game sidequests, unlocking bombchus, special rings, the Master Sword, Biggoron's Sword, and arrow/bomb capacity upgrades.
You could also get a new code to port it all BACK to your old game letting you play through the ending AGAIN with few if any additions. One Game for the Price of Two indeed.
Little known fact: If you played either game on a Gameboy Advance, there is a door that would be open in the same building as the normal shop that would be just a closed door if you played it on a Gameboy Color. If you entered the door, you would be greeted by a man telling you that you are in something called an "Advance shop". One of the things for sale is a ring. If you get it appraised, the guy appraising it will tell you that it's a ring proving that you have a Gameboy Advance. Might as well call this a Future Save Bonus.
SimCity 3000 let you import SimCity 2000 and SimCity games
SimCity 4 let you import sims from the first The Sims as citizens.
Streets of SimCity and SimCopter both let you import SimCity 2000 cities.
The Sims 2 allowed you to import small cities from SimCity 4 as a neighborhood
In a rare browser-based game example, beating Anime Versus gives you the ability to send a piece of equipment to a Billy Vs SNAKEMAN account that gives "+1 Hotness [one of the five main skills in AV, but means nothing in BVS] and +20 Daily Stamina [means nothing in AV but useful in every phase of 100%ing BVS]".
Another browser game example: Mega Man vs. Metroid and Mega Man vs. Ghosts N Goblins have interacting save files - beating Samus gets you the Missile Launcher and beating Arthur gets you the Lance, and both weapons can be used in either game. Beating both games unlocks the ability to play either game as Protoman.
Implemented similarly to Rock Band's Track Packs in Guitar Hero 5 and Band Hero with respect to Guitar Hero World Tour and Smash Hits - you only need the manual, whose code on the back is unused, and enough money to cover the cost of relicensing. The reason is that instead of exporting the data, you actually download revised data (same charts, only with new features like band moments and Expert+ for Drummers where applicable). The disc is not needed at all.
DJMAX Portable 2 has the Link Disc feature, which, with a copy of DJMAX Portable, allows you to play all of DJMAX Portables songs on Portable 2s interface. With UMDs, this is easy enough, but with ISOs, which most players are using, the process is more complicated. DJMAX Portable Clazziquai Edition's Link Disc is limited to unlocking songs in Clazziquai, and DJMAX Portable Black Square enables Portable 2-style linking with Clazziquai.
The Might and Magic series did this amazingly well, and was a rare two-way example. Characters could travel back and forth freely between games IV and V, Clouds of Xeen and Darkside of Xeen. Having both games installed at the same time also opened up a new high-level endgame called World of Xeen.
Etrian Odyssey II: Heroes of Lagaard had some minor bonuses if you entered a password obtained by beating the original game. While no characters transferred over, people recognized the name of your Guild and that you were "experienced adventurers", and several password-exclusive secrets were unlocked. note However, this also had some disadvantages, such as the tutorial guard not giving your group free Medicas because he assumed your "experienced" Level 1 heroes were strong enough to make it back without any help...
Penny Arcade Adventures allows you to keep your characters' levels by transferring a completed game save from Episode 1 to Episode 2. Any extra experience points that you earned above the initial level cap of 15 are still counted toward the next level, and will make your quest for earning level 30 a bit easier.
If you have an Ico save file on your memory card, the mark on Agro's forehead in Shadow of the Colossus will resemble the letter "I" from the ICO logo.
Save data from Yakuza will allow you to start Yakuza 2 with a collection of goodies in your item storage box, none of which you can acquire in any other way. They're presumed to be gifts from Haruka, the little girl you spend most of the first game protecting, and they include some pretty nice equipment and powerful healing items.
Professor Layton has a sort of reverse example: in addition to the first game giving you a password to unlock content in the second, the second game contains a password that can be used in the first game to unlock bonus content there, as well as a password for the third game. The third game has its own password that works in the second game. The pattern is repeated in the second trilogy of games. In all but the last two games, the passwords from future games unlock a Concept Art Gallery, while the passwords from the previous games unlock a bonus puzzle. (In the case of the last two games, using the password from Azran Legacy unlocks an extra Sequel Hook cutscene in Miracle Mask, while using the Miracle Mask password, or just having a save file on the 3DS, unlocks a concept art gallery for the whole series.)
Patapon has an unusual example; if you use the full game to load a save file created from the game's downloadable demo, it gives you a powerful, special sword for one of your troops to use.
Additionally, Patapon 2 allows you to carry over a saved file from the first game- you don't get to keep any of your troops or weapons, but you keep all of your materials, you can find a select few of your previous file's weapons during the first hunting mission, and any Rarepons you had can be made instantly without having to go through the whole evolution tree.
The two Phantasy Star Portable games have a feature similar to the Patapon example above: characters created in the downloadable demo for both games can be imported into the full games to save time and effort. In addition, importing a character from PSP1 to PSP2 allows you to import certain base features of the character's appearance (name, height, build, class), gives you whatever costume parts you had equipped on them at the time, one of four different special-effect accessories depending on your chosen class (all of which are normally received at much higher levels), the special title 'Veteran Guardian', and also gives you the Exam saber, an ice-elemental sword that is one of the most powerful single-handed swords you can get during the first chapter.
If you have a save file for Twisted Metal: Black in the game card when you start a file for War Of The Monsters, you get exclusive access to Agamo's fourth skin - patterned after Sweet Tooth.
Early Sonic example (though also applicable in Mega Collection): The number of Chaos Emeralds obtained and level reached in Sonic 3 transfers over to Sonic and Knuckles, to say nothing of the Lock-On Technology of the latter game allowing either Knuckles in Sonic 2 or the minigame Blue Sphere to be played with certain Genesis/Mega Drive games.
Jagged Alliance 2's expansion, Unfinished Business, allows to start with your party from the base game, with all the experience they gained during the playthrough. However, it adjusts the difficulty of the game accordingly.
The Tokimeki Memorial series loves to do this with their Drama Series and Substories spin-offs:
In the 3rd game of the Drama Series, Tabidachi no Uta, having a Data save of the first two Drama Series games, Nijiiro no Seishun and Irodori no Love Song, in which the games were completed at least once and have their Albums unlocked, allows you to unlock two Bonus scenarios named "Nijiiro no Sotsugyoushiki" and "Irodori no Sotsugyoushiki", which act as the True Epilogue of both games ;
In the 3rd game of the Substories series, Memories Ringing On, having a Data save of the first two Substories games, Dancing Summer Vacation and Leaping School Festival, in which the games were completed at least once and have their Albums unlocked, allows you to unlock extra dialogues and Events in the sub-characters storylines.
In Battlefield: Bad Company and its sequel, players who owned previous games in the series (or played the free game Battlefield Heroes) were considered "Battlefield Veterans" and received a free F2000 (first game) or M1 Garand (second) for use in multiplayer. Continued in Battlefield 3, where Veterans receive three versions of the M1911 for multiplayer.
If you have a savefile from Dead or Alive 3 or Xtreme Beach Volleyball on your Xbox and play Story Mode as Ein, you unlock Hitomi in Deador Alive Ultimate.
Uncharted 2 awards bonus in-game money for playing Uncharted: Drake's Fortune, up to $100,000 for unlocking the Platinum Trophy.
In the second Creatures game, an item called the Nornverter would allow you to import Creatures from the first game.
Having save data of No More Heroes on your Wii gives Travis's room an aesthetic change in the sequel.
If you connect your DS with Yu-Gi-Oh! 5Ds World Championship 2009: Stardust Accelerator to your Wii with Yu-Gi-Oh! 5Ds Wheelie Breakers, both games receive cards that you couldn't normally get without hacking them.
Rockstar Games made two games for the launch of the PlayStation 2: Smuggler's Run and Midnight Club. Players who had a save file from Smuggler's Run on their memory card got to drive the Baja Buggy from that game in Midnight Club, but only in free roam mode.
In a rather painful example, if you import a character from Alternate Reality: The City into Alternate Reality: The Dungeon, they are woefully underpowered compared to a native created character. The original concept of the Alternate Reality series was to be 8 games which, when complete would form one large world which the player could move around at will. It would not be necessary to import saves from one module to the next, the character would move to a new/previous area just by inserting the appropriate data disk (this was before hard drives were common, let alone standard equipment). Unfortunately, due to corporate problems the game only made it as far as the second installment, and ended up with a one-way import from the first game to the second.
The Expansion PackAwakening allows you to import your character from Dragon Age: Origins. If you don't take precautions you can lose all the uber-gear that was equipped on your teammates for the Final Battle, as well as most DLC gear other than that from Return To Ostagar. It's still better to start with your old character (who is already regarded as a national hero, as opposed to an interloper from a neighbouring and rival nation) from the original game than with a new one—you can start at a much higher level, with more talent and ability points if you found tomes throughout the original game.
Dragon Age II imports decisions from Origins, including some from the expansion and DLC. Most of these result in certain events getting a mention, particularly during Alistair's cameo.
The Dance Dance Revolution games for the Wii offer a varation; Hottest Party 2 can unlock all the songs on Hottest Party, Hottest Party 3 can unlock all the songs on Hottest Party 2, "Hottest Party 4" can unlock everything on Hottest Party 3, etc. The PS version of 5thMIX has options to unlock everything on 4thMIX and Extra Mix save files.
In Rainbow Six Vegas 2, you get an experience bonus based on how much experience you earned online in the first game.
The Dreamcast version of Space Channel 5 Part 2 allowed you to unlock Mr. Blank and Cecil right off the bat if you had save data from the first game.
Sonic Adventure DX and Sonic Adventure 2 Battle have Chao systems that are cross-compatible with each other as well as with the Sonic Advance games. Using the GBA it's possible to bring Chao from one game into the other. A few other games, such as the GameCube version of Phantasy Star Online included a downloadable Tails Chao that could be brought into the other games. The original Dreamcast versions of the games allowed imports from the first Adventure to the second, but not the reverse.
If you visit a certain store in Scuttle Town in Shantae: Risky's Revenge and you have a Mighty Flip Champs! and/or Mighty Milky Way save on your Nintendo DSi or 3DSnote (all three games are developed by WayForward Technologies), you'll earn some gems. Completing the games in question results in additional gems on top of those earned by merely owning the games.
Done without a memory card with Dragon Ball Z: Budokai Tenkaichi 3 through Disc Fusion on the PS2, not present in the Wii version. Having the game discs of the first two games would unlock two modes in Ultimate Battle, and clearing them rewarded you with a special item, one for each. The items aren't terribly powerful and the one item you get from collecting all items excludes these two from it's requirement.
Both the Budokai and Budokai Tenkaichi series did this off an on throughout its run - usually the reward would be the early unlock of a character (usually Bardock or another movie character) that you normally wouldn't get until much later in the game.
WWE Legends of Wrestlemania would use a save file from SmackDown vs. Raw 2009 to import characters from that game. Whilst it didn't include the entire roster (Anyone who was no longer part of the WWE roster didn't carry over) or the DLC characters, it did let players import their created characters.
Resident Evil Outbreak File #2's option menu allows you to import your purchased characters/costumes from File #1, as well as export those you purchased in File #2 back into File #1.
They planned ahead and had characters and costumes that would have appeared in File #3 had it been released, but these can only be accessed with a cheat device or by hacking the game.
In Unlimited Adventures designs, every time you save the game, the characters from your party are also saved as .cch files which can be transferred to another design (try dropping a powerful party into a low-level design and wipe the floor with all enemies). The general unwritten rule among the community is that every design should offer the player a chance to save at the very end, after all the battles are fought and all the treasure and experience is gotten; designers who forget that incur the players' wrath.
The Suffering lets you do this. The sequel not only has multiple ending but multiple beginnings. Normally you start with the neutral beginning, but having a savegame from the first game let's you chose the appropriate start.
Your Pod, outfit, and unlocked stuff in LittleBigPlanet (if you had any) is carried into the sequel upon startup. You also get a slightly altered opening narration that welcomes you back to the world of LittleBigPlanet.
This also carries over into Little Big Karting. Though you cannot import things like your pod(after all, it's big enough to fit four cars now.), you do carry over costumes and some items, DLC included.
Dissidia 012 Duodecim allows the player to transfer the levels of characters, many things unlocked from the PP Catalouge (Such as the villains and bonus chacters, costumes and player icons) as well as a few other things, from their saved data of the previous game. The player is also give the choice of importing everything, or everything but the levels (or as they call it, Restarting from Level 1.) The player can also import data from the demo bringing all the items they won in it and doing so is the only way to unlock Aerith as an assist-only character.
Split/Second: The decal "Have We Met Before?" which requires you to have a save file from Pure. It's the only decal that doesn't also grant you an achievement/trophy.
inFAMOUS 2 has various bonuses you get from getting trophies in the previous game, including bonus experience at the start and a full level of karma in whichever direction you played the previous game in.
Several of Konami's games for the MSX, when played with another Konami game in the second cartridge slot, could gain various bonuses. To list a few examples (see here for a full list):
Playing Gradius with Twinbee in the second slot, or Gradius 2 with Penguin Adventure in the second slot, would replace the Vic Viper with the other game's player character and change the power-up icons to match. This started the whimsical crossover concept that would continue in the Parodius series.
When Q*bert was placed in the second slot, it unlocked cheat codes in Gradius 2; with many other games it had the same effect as Konami's Game Master cheat cartridge.
Inazuma Eleven 3 has a "Super Link" feature where you can import many (but not all) characters from your save file on the second game. However, to prevent you from immediately assembling a team of Disc One Nukes right out of the gate, EXP and learned techniques can't be imported; you simply get a clean-slate copy of the character.
Ultimate Marvel vs. Capcom 3 will give you the DLC costumes from the vanilla release should you own them on vanilla. Also, DLC characters Jill and Shuma-Gorath will transfer over if you own them, complete with their own alternate cotumes as well. Furthermore, You unlock Galactus Mode, a special one player mode where you play as Galactus, which you would normally have to unlock via racking up 30000 player points.
Forza Motorsport 4 will handsomely reward players with a Forza 3 game save in the form of extra credits, car imports and an achievement.
Forza Horizon rewards the player who has any Forza Motorsport game save on their console with free cars, as well.
Valkyria Chronicles II will allow you to unlock several bonus characters, including Isara Gunther who died in the original game if you have save data from Valkyria Chronicles moved over from your save there. She's an Armored Tech, and a good one too.
The Flash RPG series Mardek allows the player to carry over stats and items from chapter to chapter (all chapters are separate games), along with several other variables that are carried over (conversations with NPC's, prior events being referenced in later installments, etc.)
In the Game & Watch Gallery games for the Game Boy and Game Boy Color, you can eventually unlock the ability to link with previous games in the series to unlock more Museum pictures of classic Game & Watch games. To do this between 2 and 1, you have to get over 1000 points in every game in 2; between 3 and 1, you have to get over 1000 points in every game in 1.
In Final Fantasy XIII-2, if you have a Final Fantasy XIII file, you unlock a PS3 theme or Xbox 360 gamer picture, along with the Eternal Crystal item. In addition, you can find masks of Lightning and Serah as adornments if you beat XIII.
In Dead Space 2, starting a new game with a save file from Dead Space will give you access to a "refurbished" plasma cutter - which is really just the weapon from the first game (that can't be obtained any other way). Starting a new game with a save file from Dead Space: Ignition will net you a Hacker RIG (which can be very useful in later parts of the game).
Unlocking the hidden character Jake "The Snake" Roberts in WWE Smackdown vs. Raw 2006 requires connecting with the PSP version of the same game. Yes, that's right, you need to own the exact same game on two different platforms for this one.
There is a system in Geometry Wars Galaxies for both the Wii and DS which is unlocked by linking them via wireless connection. As these are among the highest-scoring levels in the game, it is nearly impossible to ascend the scoreboard without linking.
However, the PC port scratches that (mainly because Command Mission never had a PC release), instead having you complete every area of the stage at the highest level to be allowed to meet Cut Man.
In Harvest Moon: Friends Of Mineral Town (GBA) connecting to a Gamecube with HM: A Wonderful Life unlocked Van and Ruby, from whom you could buy certain bonus items. On the flip side: playing AWL with FoMT connnected would unlock the hot springs (Where your character could recover lost health and stamina without the use of foodstuffs).
Having Resistance 2 for the PS3 linked up with Resistance: Retribution for the PSP will allow for PSP Plus, giving the player an almost entirely different storyline and locations to access within the PSP game.
Various games in the Monster Rancher franchise would generate certain special monsters by reading other Tecmo game discs, such as Dead or Alive. Previous games in the series would also unlock special monsters, as would certain CDs (or DVDs for the PS2 titles).
Fossil Fighters Champions allows you to send over fossils from the first game. This makes certain vivosaurs much easier to obtain, as some 'saurs that are only available late-game can be gotten from the start in the original FF. There are also some fossils that can only be obtained in FF, as some vivosaurs only have head fossils in Champions.note Though fossil-set completion is far less important in Champions because it's no longer tied to skill learning, it's still the fastest way to level your 'saurs.
Fable II had a little quirk which meant that in order to acheive 100% Completion on it, you also had to buy the Xbox LIVE Arcade game Fable II Pub Games, which basically used a relatively obscure gameplay mechanic of Fable II to give the player otherwise unobtainable items which were then transferable to the main game. They later released the DLC "See The Future" which allowed players to obtain the items via an in-game store tacked on with the DLC.
Due to the immortal nature of many PCs in The World of Darkness, in the Classic WoD and Vampire: The Masquerade especially, it was entirely possible to carry a PC from the 12th Century (The Dark Ages) to the 19th Century (The Victorian Age, and related) to the modern nights, and as such, you'd end up as a massively powerful being.
This is a major mechanic in Skylanders. Because the toys save all the data for the characters, it is not only possible, but encouraged to get a character to maximum level in the first game and just roll through the first few levels of the sequel.
The sequel also has an in-game "Accolade" and accompanying EXP multiplier for having Spyro, Gill Grunt, and Trigger Happy, the three characters packaged with the original game. (You can also get this by buying the sequel's versions of the characters separately, but those who bought the first game will have them by default.)
Playing Sonic the Hedgehog 4: Episode II on a system which has a saved game file for Episode I will unlock Episode Metal, in which you can play through several levels from Episode I as Metal Sonic, as well as using the updated physics engine from Episode II.
The Flash RPG series Arkandian Legends not only gives you bonuses for achievements from earlier installments but allows you to play "extra" races if you played as a particular race/faction in the previous game.
In Sleeping Dogs, having save data for Just Cause 2 will unlock a Rico Rodriguez costume for Wei Shen, which is alternatively available as DLC; true to its inspiration, the costume makes it easier to hijack moving vehicles.
The Wii U includes a built-in Wii Menu, with a Wii Shop Channel within which the Virtual Console games released for the Wii can be purchased. If you get a VC game in the Wii menu by either buying it or transferring it from the Wii, you get a discount (having to pay only $1 for NES games or $1.50 for SNES games) on the Wii U version, allowing you to pay only for the new features.
Arcade Games with card systems will often allow you to transfer data from the previous game in the series, carrying over data that would otherwise have to be earned all over again. Some examples:
Initial D Arcade Stage, up to version 3. Initial D Arcade Stage 4 uses a new card system and does not allow transfers from Ver. 3, but transfers to the next version work all the same.