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[[quoteright:350:[[VideoGame/Sonic3AndKnuckles http://static.tvtropes.org/pmwiki/pub/images/ChaosEmeralds_1761.png]]]]

[[VideoGameTropes Video games]] have {{Bonus Stage}}s that shower the hero with [[ScoringPoints points]] and [[VideoGameLives lives]], but some games go further, and place optional {{Mac Guffin}}s deep into their bonus stages. The reward for the player that hunts them all down is often a GoldenEnding or [[VideoGameRewards other reward]], but the game can be completed without them.

Usually, a bonus stage can be replayed if the Bonus Stage Collectable in it was missed the first time, but since there are limited opportunities to play the bonus stage, collecting all of the Bonus Stage Collectables is never a guarantee.

In a few rare instances, the Bonus Stage Collectables are actually hidden within the basic levels.

Most popular with side-scrollers on the 16-bit era, particularly on the SegaGenesis[=/=]Mega Drive which had battery save on far fewer games.

SubTrope of GottaCatchThemAll, which is a Sub Trope of PlotCoupon.

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!!Examples where they can be LostForever:

[[foldercontrol]]

[[folder: Franchise/Sonic The Hedgehog ]]

* ''VideoGame/SonicTheHedgehog'' has six Chaos Emeralds, each with its own special stage, which could be accessed by having at least 50 rings at the end of certain levels. If an emerald is missed, the special stage can be replayed after playing the others, but there are only 10 chances total. Collecting them all slightly changes the ending. The 8-bit version doesn't have Chaos Emeralds in the special stages; they're hidden in the regular stages instead.
** ''[[VideoGame/SonicTheHedgehog2 Sonic 2]]'' has seven emeralds. This time, special stages can be accessed through any checkpoint, leading to the potential for a lot of special stage attempts, but in practice it's tricky outside of the [[GreenHillZone first]] and [[BreatherLevel fourth]] zone. Aside from changing the ending, this game let you turn into Super Sonic with 50 rings, which meant [[GameBreaker high speed and invincibility]] at the cost of rings. The 8-bit version of this game also had the Chaos Emeralds hidden in the regular stages instead.
** ''[[VideoGame/Sonic3AndKnuckles Sonic And Knuckles]]'' (without lock-on) had a limited number of big rings hidden throughout the game which each gave one chance at an emerald. In addition to Super abilities for Sonic & Knuckles, a final, secret stage could be unlocked if the emeralds were collected as Sonic. However, as mentioned later, locking ''Sonic 3'' onto the cartridge would allow for battery saves, and infinite shots at the challenging special stages.
** ''SonicCD'' had Time Stones in the Special Stages; no Super Sonic, but getting them all and finishing the game would result in the good ending. Interestingly, there's an alternate way: if you destroy the generator found in every level's Past version, you get the good ending without needing the Time Stones.
** Later 8-bit Sonic games such as ''[[VideoGame/SonicTheHedgehogChaos Sonic Chaos]]'', ''[[VideoGame/SonicTheHedgehogTripleTrouble Sonic Triple Trouble]]'', and ''[[VideoGame/SonicBlast Sonic Blast]]'' required the emeralds to be obtained within special stages, much like the 16-bit Genesis/Mega Drive games. ''Chaos'' and ''Triple Trouble'' each have six emeralds (with five hidden in special stages and the sixth having to be recovered from the final battle with Robotnik) and ''Blast'' has five. Collecting all the emeralds in ''Blast'' grants players access to the true final battle with Robotnik.
** Later Sonic games, with a few exceptions, tied the collection of Chaos Emeralds to the plot, turning them into straight {{Plot Device}}s.

[[/folder]]

[[folder: Side Scrollers ]]

* ''{{Ristar}}'' has a bonus stage in every level, each with its own treasure. There's only one chance to get each treasure (and only if the bonus stage for that level is found). More treasures reveals more secret codes at the end of the game.
* ''[[VideoGame/CoolSpot Cool Spot]]'' has [=UNCOLA=] letters. You need a certain number of [[LawOfOneHundred spots]] (depending on the difficulty) to play the bonus round after each level, and hopefully get a letter. The best outcome is to collect and keep them all, but they can be turned in for a continue each.
* ''DynamiteHeaddy'' has seven unmissable (though skippable) opportunities for an intermission bonus stage. It needs to be cleared four times (after which it stops appearing) to get a combination number (which is re-randomized every time you start a new game) for use at the end of the game, which allows you to fight a BonusBoss if entered correctly.
* The Sega Genesis/Mega Drive version of ''[[VideoGame/RocketKnightAdventures Sparkster]]'' has the seven Holy Swords, which are similar to the Chaos Emeralds from the aforementioned ''Sonic the Hedgehog'' games. Like the 8-bit versions of ''Sonic 1'' and ''2'', the swords were hidden within certain stages. Collecting all seven swords allowed the player to face the final boss as Gold Sparkster, similar to Super Sonic.

[[/folder]]

[[folder: Turn Based Strategy ]]

* In ''[[VideoGame/FireEmblemElibe Fire Emblem: the Sword of Seals]]'', the Bonus Stage Collectables were found in the form of the eight legendary weapons. The eight legendary weapons must be obtained from completing [[BonusStage gaiden chapters]], bonus levels that could only be accessed if the previous normal chapter had all its hidden objectives fulfilled (such as completing the level before an X amount of turns have passed, keeping specific units alive, ETC) upon completion. To progress to the final arc of the campaign and gain access to the GoodEnding, you must obtain all eight of these weapons AND keep them (as well as the SwordOfPlotAdvancement and the CuteMonsterGirl's weapon) intact (they must have at least 1 charge left) before completing Chapter 22. (Obviously, said CuteMonsterGirl [[MacGuffinGirl also needs to be alive.]])

[[/folder]]

[[folder: Action Adventure ]]

* ''VideoGame/PrinceOfPersiaWarriorWithin'' had optional, hidden life upgrades spread across the game. Finding all of them was necessary to obtain the [[InfinityPlusOneSword Water Sword]] which lead to the game's TrueEnding.

!!Examples where bonus rounds can be replayed infinitely:

[[/folder]]

[[folder: Side Scrollers ]]

* ''VideoGame/DonkeyKongCountry'' 2 and 3 have unusual examples. You get bonus coins for completing the bonus stages, and these are required to get into the [[BonusDungeon Lost World]].
** ''VideoGame/DonkeyKongCountryReturns'' and ''[[VideoGame/DonkeyKongCountryTropicalFreeze Tropical Freeze]]'' fill the bonus stages with normal collectables like bananas, but collect all of them and you get a puzzle piece, of which there are only a few per level and are needed to get HundredPercentCompletion.
* ''Sonic 3'' (and by extension ''VideoGame/Sonic3AndKnuckles''). Unlike the other old Sonic games, this one had a battery save, so getting all the emeralds is a matter of time and persistence.
** Most new Sonic games use the chaos emeralds as straight-up {{Mac Guffin}}s. ''VideoGame/SonicHeroes'' is a recent exception where they follow this trope. There are keys in cages in various... [[GuideDangIt interesting]] locations throughout the stages. A Power character breaks the cage, and once the cage was broken the key just had to be picked up like a ring or some such. Losing your rings meant losing the key (due to this, people usually use Team Rose, the game's "easy mode"), and getting to the end of the stage with the key got you into the special stage after it added up your score. You could only get the Chaos Emerald if you got the key in the second stage of any theme (basically, second act) - the first act just got you points and lives. Getting all the Emeralds and completing the story for every team unlocked the Last Story (TrueFinalBoss and the true ending).
** In ''VideoGame/SonicColors'', it's actually impossible to get the Emeralds the first time through, due to the complicated procedure required to get them. First, you have to start collecting lots of special rings, of which there are five in each Act. You can start getting Emeralds once you have at least 120 of them; you need all of them to get all the Emeralds. [[DoubleUnlock Then]], you have to finish the Sonic Simulator stages unlocked by the special rings; completing all 3 in a group (for example, 1-1, 1-2, and 1-3) unlocks one Emerald. The reason it's impossible to get all the Emeralds the first time through is because some of the special rings in earlier Acts can only be reached by using Wisps unlocked later on. Getting all the Chaos Emeralds doesn't affect the story, but it does unlock the ability to play as Super Sonic; however, [[AwesomeButImpractical this disables Wisp powers]] (sometimes tweaking level layouts correspondingly), so it's more of a BraggingRightsReward.
* 6 hidden items in ''VideoGame/IWannaBeTheGuy'' serve this purpose, as collecting them all just unlocks the BossRush. However, only one of them can be LostForever, being stuffed away in the ''VideoGame/{{Metroid}}'' section.

[[/folder]]

[[folder: Platformers ( 3 D) ]]

* The Tawna bonus rounds in the first ''Videogame/CrashBandicoot1996'' let you save your game if you got to the end, and two special bonus rounds had a key which each open a secret level.
** ''Videogame/CrashBandicoot2CortexStrikesBack'' on top of gems collected by destroying all the crates (not this trope), also had death courses with gems that would open a new ending once all of them were collected. The death courses acted similarly to bonus rounds, except that dying would actually take away a life.
* ''VideoGame/ElShaddaiAscensionOfTheMetatron'' has the Bones of Ishtar hidden in a bonus level, which unlock the game's best armor. The risk is ramped up since while DeathIsASlapOnTheWrist in normal gameplay, there is a permanent death when playing those levels.

[[/folder]]

[[folder: Other ]]

* ''{{Pickory}}'' features various "secret items" to collect, most of which are hidden in optional secret levels. They do not currently unlock anything, so it's just for the extra challenge.

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