Kingdom Hearts: 358/2 Days is a perfect example. Just so you know, that's pronounced Kingdom Hearts Three-Five-Eight Days Over Two. Some people just call it Kingdom Hearts Three hundered fifty eight and a half days. Or just "Kingdom Hearts: Days", for short.
Kingdom Hearts χ [chi] is another great example. Worse than 358/2 Days, it's a Visual Pun title. The Greek letter "χ" is transliterated as "chi," but pronounced "key," as in keyblade. The game delves into the so-called "Keyblade War," a significant chapter from the series' lore.
Halo 3:ODST actually takes place concurrent with Halo 2 and has next-to-nothing to do with Halo 3, but because it was built on the Halo 3 engine it got Halo 3's number.
That said, throughout ODST, there are references to the fact that the Covenant has established a dig-site in New Mombasa to uncover...something they want really badly. Turns out, it's an artifact that creates a portal to The Ark, which is a major plot point for Halo 3. The Legendary version of the epilogue even gives an up-close view of the Artifact.
The Super Robot Wars series does this for each Alternate Continuity; Super Robot Wars F, Super Robot Wars Alpha, and Super Robot Wars: Original Generation are among the variations.
Super Robot Wars: Original Generation, and Super Robot Wars: Original Generation 2 were combined as a remake Super Robot Wars: Original Generations. Now, the combined remake is getting a sequel: 2nd Super Robot Wars: Original Generation. So the second game is the 4th release and set after the one numbered 2. Okay.
The Harvest Moon series has done this almost to an extreme. Except for some versions on Nintendo portables (which are simply named Harvest Moon 1, 2, 3 and DS) and the PSP version, every sequel has a new name: Harvest Moon: Back to Nature, Harvest Moon: Friends of Mineral Town, Harvest Moon: A Wonderful Life, Harvest Moon: Save the Homeland, Harvest Moon: Magical Melody, Harvest Moon: Tree of Tranquility, Harvest Moon: Island of Happiness, Harvest Moon: Animal Parade, and Harvest Moon: Sunshine Islands. Also, many of these have a For Girls version, with a twisted name (such as Harvest Moon: Another Wonderful Life); the Japanese versions of these just tacked on a "For Girl".
Also,"Harvest Moon DS Cute".
Because as you know, Cute = girl.
The Duke Nukem series: not counting spinoffs, Duke Nukem, Duke Nukem II, Duke Nukem 3D and Duke Nukem Forever. As a funny note, it started out as Duke Nukem, but was quickly released as Duke Nukum because of a Captain Planet and the Planeteers character with the "Duke Nukem" name. When the sequel was being developed, the developers discovered that the Captain Planet character's name had not been registered, so the sequels all use the original Duke Nukem name.
No One Lives Forever: the original game was titled The Operative in No One Lives Forever however for the sequel they turned the original subtitle into the main title, resulting in No One Lives Forever 2: A Spy in H.A.R.M.'s Way.
Let's not even mention the terrible sequel/prequel known simply as Contract J.A.C.K.
There's also the portable side-game, Metal Gear Solid: Peace Walker (which at one point was considered Metal Gear Solid 5 by the development team), as well as the multiplatform release Metal Gear Solid V: The Phantom Pain (switching from Arabic to Roman numerals), before which Metal Gear Solid Ground Zeroes was thought to be the next game in the series until it was revealed to just be the prologue chapter.
Marathon was followed by Marathon 2: Durandal which was followed by Marathon Infinity. Infinity was then given a joke award by MacFormat for "largest version number increase." As if this wasn't enough, the game engine for Marathon 2 was subsequently released and developed into an open-source version named Aleph One, thereby restoring/continuing sequential numbering at the expense of not being understandable by anyone who wasn't a math major. (Partially justified in that much of the "plot" of Infinity was based on universe hopping and the game was released with the creators' level-design, physics-editing, and graphics-editing tools so that players could make their own stories, making the game "infinite.")
Banjo-Kazooie was followed by Banjo-Tooie, which made in-game mention of a Banjo-Threeie that led some people to believe that the third game would be called that. The third game instead ended up being called Banjo-Kazooie: Nuts & Bolts.
Panzer Dragoon was followed by Panzer Dragoon II Zwei, Panzer Dragoon Mini, Panzer Dragoon Saga, and Panzer Dragoon Orta.
In World of Warcraft, after doing the quest "Here Fishy Fishy", you get a followup involving an eel egg booby trapped with explosives. The quest name? Why, "Here Fishy Fishy 2: Eel-egg-trick Boogaloo," of course.
Dissidia: Final Fantasy started off as merely suffering from Gratuitous Latin. But then the sequel is named Dissidia 012: Final Fantasy (where Dissidias 2 through 11 went we'll never know). Except it's supposed to be pronounced Dissidia Duodecim: Final Fantasy, because once again, Gratuitous Latin. To really drive the point home and avoid another 358/2 Days confusion, they've helpfully included the correct pronunciation in the game's logo. Only now it actually gets MORE confusing because the logo now reads Dissidia [duodecim] 012: Final Fantasy. Just calling it Dissidia 2 would have been perfectly fine, Square-Enix.
The first Dissidia is Dissidia 13; that is, in Dissidia, the war between Cosmos and Chaos is an endlessly repeating cycle, with the original Dissidia chronicling the thirteenth repetition of said cycle. Duodecim is a prequel covering the twelfth repetition. Which is not confusing at all.
Super Smash Bros.. was followed up with Super Smash Bros. Melee and Super Smash Bros. Brawl. The upcoming release(s) being "Super Smash Bros. for Wii U" or "for 3DS" (but when you think about it for and four are pronounced the same)
The Japanese naming conventions are even weirder. Nintendo All-Star: Dairantou Smash Brothers [sic], Dairantou Smash Bros. DX (DX is short for "Deluxe"), and Dairantou Smash Bros. X. All words in English in the title are actually that way, by the way. "Dairantou" roughly translates to "Melee" or "Brawl."
In North America, the sequel to Rival Schools: United By Fate was named simply Project Justice. In all other regions, the connection was made more clear - in Japan, the game was titled Moero! Justice Gakuen (the original game was Shiritsu Justice Gakuen) while other regions used the Project Justice name but tacked on Rival Schools 2 at the end.
It didn't help that the Japan-only Updated Re-release of the original game was titled Shiritsu Justice Gakuen: Nekketsu Seisyun Nikki 2. The number was for the updated character creation mode (the Nekketsu Seisyun Nikki part of the title) included in the game, but the number's inclusion caused everyone outside of Japan to mistake it for a sequel.
And then there's Tales of Vesperia. Considering that, from what this troper can tell, there is little to no (besides bonus bosses) relation to the other Tales games.
Despite five entries (split in 19 games) in the main series, there has never been a Pokémon 2, let alone 3, 4 or 5, despite the fact that the second generation was indeed a direct sequel to the first one, and that the Sinnoh games (Generation IV) were a semisequel to Generation II. Every game after the first generation (whose games were named after colors) is merely titled "Pokémon" plus a precious material (gold, silver, crystal, ruby, sapphire, emerald, diamond, pearl and platinum) for subtitle. Since Pokemon games come in pairs (and by the end of the generation they end up being a trio), non-hard-core fans might have a hard time when trying to figure out which versions are paired with each other and distinguish the generations. Generation V switching back to colors (Black and White) sort of made things easier, but still is a non-indicative name (and after three generations of metal/jewel based titles, it becomes itself an odd theme). For those wondering, terms like the "second generation" or "Generation V" are only Fan Nicknames for groups of games and the Pokémon within them (which also distinguish remakes from the originals).
Among the spinoffs, the original Pokémon Ranger is followed by Pokémon Ranger: Shadows of Almia and Pokémon Ranger: Guardian Signs, Pokémon Mystery Dungeon had its first games bear the subtitles "Red Rescue Team" and "Blue Rescue Team: (which, even more confusingly, aren't even on the same system as one another), followed up by "Explorers of Time/Darkness/Sky" and then the Japan-exclusive "Adventure Squad", and Pokémon Colosseum's sequel is called Pokémon XD: Gale of Darkness.
Within the series' context, the main series titles have their own Oddly Named Sequels in the form of Black 2 & White 2.
And the trope is even parodied in the latter: in the game you can find a pile of "old rejected movie scripts". One of them is titled "Galvantula's Travels 2: Eelektrik Boogaloo".
All three Xenosaga games take their subtitles from Nietzche: Der wille zur Macht, Jenseits von Gut und Bose, and Also Sprach Zarathustra. They also precisely reversed the order Nietzche originally wrote them in - Also Sprach Zarathustra was first published from 1883-1885, Jenseits von Gut und Bose in 1886, and Der Wille Zur Macht was compiled, edited, and published post-humously by his sister. Presumably, the planned Episodes 4-6 would have continued to borrow from his earlier and earlier works for titles as well.
Ace Attorney has this. While the Japanese sequels are Gyakuten Saiban 2-4 and Gyakuten Kenji for the spinoff, they were translated as Phoenix Wright: Ace Attorney, Phoenix Wright: Ace Attorney: Justice for All, Phoenix Wright: Ace Attorney: Trials and Tribulations, Apollo Justice: Ace Attorney, and Ace Attorney Investigations: Miles Edgeworth. We may need an oncologist in here.
Probably has to do with the fact that the localization staff chose the title for the first game before learning that the fourth game would have a new protagonist. Thus, the Ace Attorney part was promoted as the main title for the rest of the series, while Phoenix Wright was demoted to a subtitle in the sequels.
No less a video game personnage than Mario has been responsible for this, multiple times. First, the sequel to Mario Bros.. was named Super Mario Bros.. This was numbered sanely until the Super Nintendo came along, when his fifth console game became Super Mario World (although it was actually known as Super Mario Bros. 4: Super Mario World in Japan). The sequel to that was called Super Mario World 2: Yoshi's Island, and then the series split - the Yoshi's Island games became their own series, while Mario stopped even bothering with numbering them in sequence (until Super Mario Galaxy 2). Something similar to the Yoshi's Island rename happened to the Super Mario Land games for the Game Boy, in which the third game was Super Mario Land 3: Wario Land, which spun off into the Wario Land series.
The initial Super Mario Bros. series is numbered sanely only in the Western markets: the game released in the West as Super Mario Bros. 2 was released as "Super Mario Bros. USA" in Japan — the game known in Japan as Super Mario Bros. 2 was released as part of a compilation game in the West years later under the title Super Mario Bros.: The Lost Levels.
And then there are the remakes for the GBA. Super Mario Bros. 2 became Super Mario Advance. The worst offender is the GBA remake of Super Mario Bros. 3, titled "Super Mario Advance 4: Super Mario Bros 3".
Resident Evil: Code: Veronica was intended to be the true sequel to Resident Evil 2, but since the game was originally being developed on the Dreamcast instead of the PlayStation like the previous games, Sony threw a hissy fit, forcing Capcom to relabel the game as a spin-off and leave it off the numbered series. At the same time, Resident Evil: Nemesis, a side-story game that was being developed on the Resident Evil 2 engine, ended up being released as Resident Evil 3: Nemesis instead. Funnily enough, Resident Evil 4 ended up being developed for the Nintendo GameCube when Capcom eventually got around to making it.
Another oddity is that the logo of Resident Evil 4 actually gives the number first, making it technically "4 Resident Evil."
The game series now known as Legacy of Kain started with the game Blood Omen: Legacy of Kain with the weighting making it apparent the 'Legacy of Kain' part was a subtitle. A few years later the next game came out called Legacy of Kain: Soul Reaver (blood no longer being much of a big deal to the wraithlike new hero Raziel). It was followed by Legacy of Kain: Soul Reaver 2...but then came Legacy of Kain: Blood Omen 2, which thoroughly confused everyone. The 2 sub-series finally converged in the final game, Legacy of Kain: Defiance- to everyone's great relief.
The numerous Street Fighter installments by Capcom with their various adjectives, suffixes, and subtitles can be a bit confusing to first-time fans of the series. This is because Capcom considers every Roman numbered entry in the franchise after the first game to be its own sub-series, making it a bit harder to number specific entries in each sub-series.
Street Fighter II: The World Warrior was followed by Street Fighter II (Dash): Champion Edition, Street Fighter II (Dash Turbo): Hyper Fighting, Super Street Fighter II: The New Challengers, and Super Street Fighter II Turbo (aka Super Street Fighter II X: Grand Master Challenge). Those are just the original arcade releases. Some of the console-specific variants include Street Fighter II Turbo for the SNES, Street Fighter II: Special Champion Edition for the Genesis (both were compilations of Champion Edition and Hyper Fighting), Super Street Fighter II Turbo Revival for the GBA (a portable version of Super Turbo), Hyper Street Fighter II: The Anniversary Edition for the PS2 and Xbox (a pseudo-compilation of the five arcade games), and Super Street Fighter II Turbo HD Remix for the PS3 and Xbox 360.
Street Fighter Alpha: Warriors' Dream (aka Street Fighter 0) was followed by Alpha 2 and Alpha 3 on the arcades. Alpha 2 and Alpha 3 both had their share of minor upgrades. Alpha 2 had Alpha 2 Gold for the PS1 and Saturn (aka 0 2 Dash, which in turn was based on a minor Asia-only arcade upgrade called 0 2 Alpha), while Alpha 3 was followed by Alpha 3 Upper for the GBA (which took its title from 0 3 Upper, a Japan-only arcade upgrade with the roster additions from the console ports) and Alpha 3 MAX (aka 0 3 Double Upper).
The Street Fighter EX series consists of EX, EX Plus, EX Plus Alpha (a PS1 port of the previous game), EX 2, EX 2 Plus (which also had a PS1 port), and EX 3 (a PS2-exclusive).
Street Fighter III: New Generation was followed by Street Fighter III 2nd Impact: Giant Attack and Street Fighter III 3rd Strike: Fight for the Future. Sometimes, the 2nd Impact and 3rd Strike portions of their respective titles are treated as subtitles rather part of the main titles (in such cases, the actual subtitles of Giant Attack and Fight for the Future are omitted).
Street Fighter IV was followed by Super Street Fighter IV, which was followed by Super Street Fighter IV: Arcade Edition. There's also the 3D Edition of Super for the 3DS.
In Japan, the Slam Masters (or Muscle Bomber) series is comprised of Muscle Bomber, Muscle Bomber Duo, and Super Muscle Bomber. The corresponding English versions of these three games are Saturday Night Slam Masters, Muscle Bomber Duo, and Ring of Destruction: Slam Masters II. In other words, the series got its title changed to Slam Master for the English version of the first game, and then changed back to Muscle Bomber for the second, only to be changed back to Slam Masters for the third.
Samurai Shodown: Warriors Rage for the PlayStation is not a port, but a distant sequel to the similarly titled Hyper Neo Geo 64 arcade game Samurai Shodown 64: Warriors Rage (which itself was a sequel to the original Samurai Shodown 64). The Japanese versions averted this by being named differently.
The European/Japanese-only sequel to Trace Memory (Another Code in those regions) was titled Another Code R: A Journey Into Lost Memories (Gateway of Memory in Japan.)
Due to legal issues, the PlayStation version of Soul Edge was renamed Soul Blade in America and Europe. To sidestep this legal hurdle, the sequels were released under the Soul Calibur name instead. Thus Soulcalibur V is actually the sixth game in the series.
It gets even more confusing in terms of capitalization. The "Soulcalibur" series started off as Soul Calibur, and its sequel, Soul Calibur II reflects this. With the game's third entry, the series was renamed Soulcalibur (all one word), so the the title of the game became Soulcalibur III. In addition, the previous two games were retroactively renamed under this system (Soulcalibur and Soulcalibur II, respectively). Thankfully, the nomenclature has remained since III.
The Soul Series isn't immune to subtitles, too - the arcade revision of Soulcalibur III was named (you guessed it) "Soulcalibur III: Arcade Edition". The re-release of Soulcalibur IV for the PSP was titled "Soulcalibur: Broken Destiny".
The sequel to Battle Clash is titled Metal Combat: Falcon's Revenge. The only indicator on the title that Metal Combat is a sequel is the fact that the hero's mecha in both games is called the "ST Falcon".
Darkstalkers (aka Vampire in Japan) was followed by Night Warriors (Vampire Hunter) and Vampire Savior (which was almost titled Jedah's Damnation in America until they decided to stick with Vampire Savior). To make matters more confusing, Japan received two simultaneously released updated rereleases of Vampire Savior titled Vampire Savior 2 and Vampire Hunter 2; the main difference between the three games are in their character roster. The PlayStation game Darkstalker 3 (aka Vampire Savior: EX Edition) is actually a pseudo compilation of Vampire Savior, Vampire Savior 2, and Vampire Hunter 2.
Capcom's first JoJo's Bizarre Adventure fighting game for the arcades was released internationally under the shortened title of Jojo's Venture. The sequel, which was titled Jojo's Bizarre Adventure: Heritage for the Future in Japan, was released under the manga's full title of Jojo's Bizarre Adventure internationally. The PlayStation and Dreamcast ports had no such titling issues.
The Anno Domini series of historical city builders (known as A.D. in some markets) goes back and forth between the centuries. First there was Anno 1602, followed by Anno 1503, then Anno 1701, Anno 1404 and finally Anno 2070. Even odder since the numeration could lead a newbie to think 1701 is the first, with the series going backwards 99 years with each installment.
In addition to all this in some markets the latest installment Anno 1404 is sold as Dawn of Discovery. This in turn has an expansion pack which is known as both Anno 1404: Venice and Dawn of Discovery: Venice.
Interestingly, the dates always add up to the number nine.
Shinobi III may sound like a sensible name for a sequel, until you realize it's not literally the third game in the Shinobi series at all. Although, it is the third Shinobi game for the Sega Genesis, the first two Genesis games were already sequels to previous Shinobi games. The first Genesis game, The Revenge of Shinobi, is a sequel to the Master System version of the first Shinobi, which itself was based on an arcade game, while Shadow Dancer: The Secret of Shinobi, the second Genesis game, was itself a loose sequel to the arcade's Shadow Dancer, which was the arcade sequel to Shinobi. That's not even counting The Cyber Shinobi: Shinobi Part 2, the European-exclusive Master System sequel to the first Shinobi. So which game could be considered the "true Shinobi II"? The game system of Shinobi III is clearly based on The Revenge of Shinobi and the Japanese versions of both games makes their relation a lot less ambiguous, since they're titled The Super Shinobi and The Super Shinobi II.
Tradewest's fighting game based on the Double Dragon cartoon was titled Double Dragon V: The Shadow Falls, which was released for the SNES and Genesis (as well as the Jaguar), even though it had nothing to do with the previous Technos-developed games and there was no "Double Dragon IV". While technically there was a fourth Double Dragon game, it was an SNES-exclusive installment titled Super Double Dragon, meaning that the owners of the other consoles would've not been aware of it.
The second Tetris: The Grand Master game's name is a source of minor confusion; fans have a hard time decising whether it's Tetris: The Grand Master 2 - The Absolute or Tetris: The Absolute - The Grand Master 2. Then there's Tetris: The Grand Master 3 - Terror-Instinct, Tetris: The Grand Master ACE (a spinoff of TGM), and Tetris: The Grand Master 4 - The Masters of Round (technically the fifth game in the series).
The sequel to Galaga was called Gaplus, then was rereleased under the name Galaga 3. There is no Galaga 2.
And then, of course, Galaga '88. Does the absence of intervening numbers need to be brought up again?
The virtually unknown Real-Time StrategyEarth 2140 has a much more successful sequel named Earth 2150 (or Earth 2150: Escape from the Blue Planet), which itself has 2 stand-alone Expansion Packs named Earth 2150: The Moon Project (some editions drop Earth 2150) and Earth 2150: Lost Souls. The third full game in the series is, consequently, named Earth 2160, even though Earth itself is gone by that point in an Earth-Shattering Kaboom, and the entire game takes place on other planets. Apparently, it is a rule in the series that a major conflict has to take place every 10 years.
Mushihime-sama's sequel is called Mushihime-sama Futari. "Futari" means "two people."
The Divinity series gets to be oddly named from the very beginning, but the sequels make their own kind of nonsense. In order: Divine Divinity, Beyond Divinity, Divinity II: The Dragon Knight Saga (which is itself made up of Divinity II: Ego Draconis and Divinity II: Flames of Vengeance). Divine Divinity was meant to be Divinity: Sword of Lies, and Beyond Divinity was a spinoff; Ego Draconis was the original Divinity II game, which was rereleased as The Dragon Knight Saga as a bundle or as just the expansion, Flames of Vengeance.
Tecmo's Deception was followed by Kagero: Deception II and Deception III: Dark Delusion. Okay, at least they're numbered. Then Tecmo calls the fourth game Trapt. Now they're publishing the newest game abroad as Deception IV: Blood Ties.
The Panzer General series, as released in Germany. The first one was still Panzer General, the (Panzer General II) became Panzer General 3D (even though it wasn't 3D), and then the actual Panzer General 3D became Panzer General 4. Faces where palmed.
According to the developers, this is due to it being set in the same universe, but having few connections to the previous games besides the main character.
In the case of Need for Speed, ordering the Hot Pursuit subseries while give you a headache: Need For Speed III: Hot Pursuit, then Need For Speed: Hot Pursuit II, and then Need for Speed: Hot Pursuit. Yes, the completely unnumbered title is the sequel to the game that's number two.
Love Plus then Love Plus+ and now for the 3DS Project Love Plus.
In Japan, the third game of the Strikers 1945 series is called Strikers 1999 to reference the Setting Update. Everywhere else, it's called Strikers 1945 III.
Wonder Boy probably has the most confusing series of sequels out of all the examples listed here thanks to the numerous alternate titles the games had between different platform ports and regional releases.
The first game itself, originally an arcade release, is also known as Super Wonder Boy on the Japanese Master System (since it has a few enhancements from the arcade version and there was also an earlier Wonder Boy port released in Japan for the SG-1000, Sega's first game console) and Revenge of Dracon on the American Game Gear (it was still called Wonder Boy everywhere else).
The second entry in the series was Wonder Boy: Monster Land for the arcade, which was ported to the Master System in Japan under the name of Super Wonder Boy: Monster World and that particular version was released in the west as Wonder Boy In Monster Land (the "in" was not present in the arcade version's title).
The third and last of the arcade releases was titled Wonder Boy III Monster Lair. The console ports for the TurboGrafx-16 and Mega Drive both kept the same name this time, although the cover artwork for the TG16 version omits the "Wonder Boy III" portion.
The fourth entry is when things start to get confusing. The game was released for the Master System in the west as Wonder Boy III: The Dragon's Trap (titled as such since it was the third Master System game in the series), which is a distinct game from the aforementioned Wonder Boy III: Monster Lair. The Master System version was supposed to be released in Japan as Monster World II, but that version got canceled. Instead, the later Game Gear port (which was simply titled Wonder Boy: The Dragon's Trap in the west, dropping the numeral altogether) came out there as Monster World II: Dragon no Wana.
The next entry was Wonder Boy V: Monster World III for the Mega Drive (simply titled Wonder Boy In Monster World in the west, not to be confused with the aforementioned Super Wonder Boy: Monster World, the Sega Mark III version of Wonder Boy in Monster Land). Despite its Japanese title, Monster World III is actually the fourth game in the series released in Japan, since Monster World II (which fills the position of "Wonder Boy IV") was only released a few months later in Japan, unless we count the Dragon's Curse/Adventure Island remake by Hudson Soft (which opens a whole 'nother can of worms).
Monster World IV is the sixth and final game in the series. It drops the Wonder Boy name completely since the protagonist in this one is a girl.
The Call of Duty franchise is actually handed back and forth between two developers, after the fourth installment the sequels changed as each went in their separate directions. Call of Duty 4: Modern Warfare begat Call of Duty: Modern Warfare 2 (the "Call of Duty" was largely omitted from advertising) which begat Call of Duty: Modern Warfare 3. Call of Duty: World at War followed 4, then Call of Duty: Black Ops, and then Call of Duty: Black Ops 2.
The name Tiberian Dawn had been used by Westwood in pre-release materials, and even appeared in the readme.txt file, but didn't appear anywhere in the original game or its packaging, so didn't see widespread use among fans until it became necessary to differentiate the first game from the series as a whole.
The main series has always had Numbered Sequels, up until the prequel OVERKILL. There's also the small oddity of 3 being set after 4 (apparently huge time skips were all the rage at the time of 3's release, only for Sega, like everyone else in that bandwagon, to realize now there was nowhere left to go except backwards).
The Star Wars: Dark Forces games have a strange number sequence. They start with Dark Forces, followed by Jedi Knight: Dark Forces II, then Jedi Knight II: Jedi Outcast and finally Jedi Knight: Jedi Academy. Even worse when you see that LucasArts (and no one else) considers the full titles to all be prefixed with "Star Wars."
The first sequel to Myst was called Riven: The Sequel to Myst. Later games adopted a more conventional numbering scheme, resulting in Myst III: Exile, Myst IV: Revelation, and Myst V: End of Ages. A spinoff also exists, which went through enough name changes between its development, release, the cancellation of its online component, the resurrection of its online component through GameTap and its second cancellation that it probably deserves its own trope. The last name it had was Myst Online: Uru Live.
Apparently the English-speaking world needs their sequels to have subtitles. Shadow Hearts 2, as it is called in Japan, was changed to Shadow Hearts: Covenant for the English version. The third game followed suit, and was called Shadow Hearts: From the New World in all versions.
And let's not forget that they're all sequels to a game called Koudelka.
Splinter Cell, as the picture above indicates, has some idiosyncratic titling. The series goes as thus: Tom Clancy's Splinter Cell, Tom Clancy's Splinter Cell: Pandora Tomorrow, Tom Clancy's Splinter Cell: Chaos Theory, Tom Clancy's Splinter Cell: Double Agent, Tom Clancy's Splinter Cell: Essentials (which, despite the name, isn't a remake package with the original games), and Tom Clancy's Splinter Cell: Conviction.
Though to their credit, they never tried to mix numbers in with their subtitles. Considering how the naming schemes of some other series turn out, that is probably a good thing.
This was actually caused by Executive Meddling. Originally Chaos Theory was supposed to be the sequel to Splinter Cell and thus known as Splinter Cell 2. Pandora Tomorrow was only supposed to be an expansion pack to the original. When it was decided that Pandora Tomorrow would be a stand-alone title they released it without any numbering to avoid confusing people.
The early Mega Man sequels were numbered with Roman numerals (at least on the title screens), but this became problematic when Capcom released a spin-off game for the SNES named Mega Man X (as in the letter "X", not a Roman numeral 10), which was followed by its own series of numbered sequels. Because of this, Capcom switched to Arabic numerals for both the box art and title screens in the original series starting with Mega Man 8 in order to avoid any confusion, as the franchise eventually had a real Mega Man 10. This was never a problem in Japan, where the original Rockman games always used Arabic numerals.
While the games for the Game Boy shared the same names as the ones that were released for the NES (except the first one, which was titled Mega Man in Dr. Wily's Revenge), there were not actually ports of their corresponding NES games, but remixed versions that combined bosses from the corresponding NES game with those from its succeeding installment (i.e. Dr. Wily's Revenge has bosses from the firsttwo NES games, the Game Boy version of II has bosses from the NES version of II and III, and so on). The only exception was the Game Boy version of Mega Man V, which features all new bosses instead of borrowing the ones from the NES games. The Japanese versions of these games were released under the Rockman World name, helping Japanese fans tell them apart.
Lampshaded in the fourth chapter of Tales of Monkey Island, with a souvenir pin reading "Trial of the Century II: Electric Voodooloo".
Bethesda have explained that New Vegas isn't a sequel to 3, so it doesn't follow in number (if anything, it's more of a sequel to the never-releasedFallout: Van Buren). Bethesda are apparently planning their own sequel at some point, so presumably that'll be 4.
Oh, boy. Guilty Gear is chock full of these, too. The second Guilty Gear game is Guilty Gear X, and the X sure doesn't stand for the Roman numeral (apparently it's pronounced "Zex"). After that, it's Guilty Gear XX (pronounced "Igzex"). And then come its re-releases, #Reload (pronounced Sharp-Reload), Slash, and Λ Core (Accent Core). And Accent Core Plus, the updated release of an updated release (that's right, the full title is "Guilty Gear Igzex Accent Core Plus"). There's also the spin-offs Isuka, Judgment, and Dust Strikers (they aren't preceded by the XX, though), but they're more like Mission Pack Sequels. Guilty Gear X [By your side "G. Gear"] too.
Technically, the true sequel to Guilty Gear is Guilty Gear 2: Overture.
XX later received a fifth update, entitled Guilty Gear XX Accent Core PlusR. In an attempt to outdo themselves again, Arc System Works then announced a new installment, Guilty Gear Xrd -SIGN-, which mixes this trope with Sequel Number Snarl (the Xrd, pronounced "igzird", can be read as "X third", and thus "three Xs", following the lead of the X and XX subseries, despite the fact that Xrd is essentially GG3).
After Leisure Suit Larry 7: Love for Sail!, the series was spun-off into a new direction with a new character (Larry's nephew, also named Larry), and the numbering scheme was abandoned. The nephew's games (which sometimes have the original Larry voice letters sent to his nephew) include Leisure Suit Larry: Magna Cum Laude, Leisure Suit Larry: Box Office Bust, and the cancelled Leisure Suit Larry: Cocoa Butter.
After Dwarf Fortress retroactively sequelized to follow the defunct Slaves to Armok: God of Blood, it is now Slaves to Armok: God of Blood Chapter II: Dwarf Fortress, subverting Exactly What It Says on the Tin since it doesn't feature Armok in any way and dwarves do not keep slaves.
Technically Dwarf Fortress is followed by yet another random subtitle, Histories of <synonym of greed> and <synonym of hard work>, ie. Slaves to Armok: God of Blood Chapter II: Dwarf Fortress: Histories of Gluttony and Determination.
Star Ocean games have Star Ocean, Star Ocean: The Second Story, Star Ocean: Blue Sphere, Star Ocean: Till the End of Time and Star Ocean: The Last Hope (simply titled Star Ocean 4 in Japan). The first two games were later remade under the titles Star Ocean: First Departure and Star Ocean: Second Evolution. Not to mention The Anime of the Game, Star Ocean EX, which is apparently based on The Second Story.
There were actually two Wonder Boy III games. The first, Monster Lair, is an In Name OnlyShoot 'em Up sequel to the arcade version of Wonder Boy in Monster Land, which has a different ending than the SMS version, while the second, The Dragon's Trap (Dragon's Curse on the TurboGrafx-16), is a direct sequel to the SMS version of Monster Land.
The Total WarSeries is an interesting take on this, not only does it usually put the series name after the subtitle but it uses numbers and/or sub-subtitles for some games but not for others. In order of release the games go, Shogun: Total War, Shogun: Total War: Mongol Invasion, Medieval: Total War, Medieval: Total War: Viking Invasion, Rome: Total War, Rome: Total War: Barbarian Invasion, Rome: Total War: Alexander, Medieval II: Total War, Medieval II: Total War: Kingdoms, Empire: Total War, Napoleon: Total War and just to make the naming even more confusing Total War: Shogun 2 and Total War: Rome II.
Trackmania, Trackmania Sunrise, Trackmania Nations, Trackmania United Forever, Trackmania Nations Forever... and the brand new Trackmania 2! (Not counting console spinoffs)
The Guitar Hero saga, only counting home consoles releases *deep breath*: Guitar Hero, Guitar Hero II, Guitar Hero: Rocks the 80's (spin-off), Guitar Hero III: Legends of Rock', Guitar Hero: Aerosmith(band-focused), Guitar Hero: World Tour, Guitar Hero: Metallica (again, band-focused), Guitar Hero: Smash Hits (another spin-off), Guitar Hero 5, Band Hero (yet another spin-off), Guitar Hero: Van Halen (yep, band-focused again) and Guitar Hero Warriors of Rock.
And there's the portable games: Guitar Hero: On Tour, Guitar Hero On Tour: Decades and Guitar Hero On Tour: Modern Hits.
The WWF Smackdown games start off with the first one and the second ones using numbers (Smackdown 2: Know Your Role), but as of the third one stopped using numbers, as of the sixth one started using the title "Smackdown vs. Raw" instead, and as of the seventh one started including the year a la Madden.
In Japan, the Samurai Spirits games in general have their own Word Salad Title such as II being "Shin Samurai Spirits: Haohmaru Jigokuhen" (True Samurai Spirits: Haohmaru's Vision of Hell), III is Samurai Spirits: Zankuro Musouken (Peerless Sword of Zankuro), IV is Samurai Spirits: Amakusa Kourin (Amakusa's Advent), and V is actually known as "Samurai Spirits Rei" (Samurai Spirits Zero). It helps to know that the order of the main games (I-V) is V, I, III, IV, II. The two SS 64 games take place after II, and Sen takes place after the 64 games.
Gargoyle's Quest and Gargoyle's Quest II came out for the Game Boy and NES, respectively. They were followed by Demon's Crest on the Super NES. Their Japanese names weren't any better, the first two games being named Red Arremer I and II, and then the third game being called Demon's Blazon.
It seems that the developers want to keep changing the numbers only for games when a new main character is introduced. On the other hand, some naming choices, such as Assassin's Creed III: Liberation, which features a completely different character unrelated to the others (except also being an ancestor of Desmond), do help throw off some people.
Gex was followed up by Gex: Enter the Gecko and then Gex 3: Deep Cover Gecko.
The Puzzle GameTant-R had sequels named Ichidant-R and Sando-R. "Ichidan" means "more" and "sando" means "three times."
During the 90s, Electronic Arts released a series of helicopter-based shooters named the "Strike series". The series consists of Desert Strike, Jungle Strike, Urban Strike, Soviet Strike and Nuclear Strike.
Magical Drop F: Daibouken mo Rakujanai!, where "F" stands for four.
The Clock Tower series gets this, mainly due to localisation:
The first game, known as just Clock Tower in Japan, remained untranslated on the Super Famicom, and was not released internationally until the year after it came out, as a port on the Playstation, being named Clock Tower: The First Fear. This was considered necessary, because...
Not much later, another game, called Clock Tower 2 in Japan, was released internationally as just Clock Tower.
Later, an offshoot game with little to do with the previous games, called Clock Tower: Ghost Head in Japan, was named Clock Tower II: The Struggle Within in international releases.
Thankfully, this ended with Clock Tower 3, which has the same name for everyone.
Serious Sam: The Second Encounter (or "TSE") and Serious Sam 2 (sometimes referred to as "SS2"" or "II") are actually two different games. The former is a Mission Pack Sequel to the original, while the latter is a completely new installment—released well after The Second Encounter—with its own art style, setting and story line. Both of these were followed by Serious Sam 3: BFE ("Before the First Encounter") a prequel to the original game (referred heretofore as "TFE", or "The First Encounter"). And that's not counting Serious Sam HD and Serious Sam: The Second Counter HD which are Updated Rereleases of TFE and TSE, respectively.
The arcade version of Silent Scope 2 was titled Dark Sillhouette: Silent Scope 2, although the PS2 version switched the titles back around.
The Elite series seemingly follows no naming convention whatsoever. It started with Elite, then the sequel was Frontier: Elite II, followed by Frontier: First Encounters, and now Elite: Dangerous is in the works.
A slight example in Space Quest. Each game is consistently named with a Roman numeral followed by a subtitle (except the first game that doesn't feature a number, of course). Starting with the fourth game, the developers have decided to include the main character's name in the subtitles, even when removing it would sound better (e.g. Space Quest IV: Roger Wilco and the Time Rippers, Space Quest V: Roger Wilco – The Next Mutation). The sixth game uses an Arabic numeral out of the blue (Space Quest 6: Roger Wilco in The Spinal Frontier). The working title for the cancelled seventh game was Space Quest VII: Return to Roman Numerals as a nod to the break in numbering.
The BIT.TRIP series was named consistently, starting with BIT.TRIP BEAT, then BIT.TRIP CORE, BIT.TRIP VOID, BIT.TRIP RUNNER, BIT.TRIP FATE and BIT.TRIP FLUX, until came BIT.TRIP Presents... Runner2: Future Legend Of Rhythm Alien, justified since the latter can be considered a spin-off, but can also be considered a sequel to RUNNER.
The sequel to Speedball was titled Speedball 2: Brutal Deluxe, where "Brutal Deluxe" was the name of the player team. (The subtitle could have been something like "Electrobounce Boogaloo"; mercifully it wasn't.)
In Japan, Toaplan's sequel to Tatsujin (Truxton elsewhere) was titled Tatsujin-Oh ("Expert King"), written in kanji rather than romaji as with the first game.
Solomon's Key 2 was subtitled Coolmin Tou Kyuushutsu SakusenTranslation "Coolmin Tower Rescue Mission" in Japan.
The sequel to Hotline Miami is titled Hotline Miami 2: Wrong Number.
Ikari Warriors was followed by Ikari Warriors II: Victory Road and Ikari III: The Rescue. Though only the Nintendo Entertainment System version of Victory Road carried the Ikari Warriors II title, the original Japanese title, Dogosoken, had a kanji title beginning with the same character as "ikari."
The King's Field series can be confusing, because the first game was only released in Japan, so "King's Field" and "King's Field II" outside Japan are "King's Field II" and "King's Field III" in Japan. The last one is variously called "King's Field: the Ancient City" or KF III or KF IV.