The background music of the first level in many video games frequently becomes the theme associated with the series. Sometimes, the "first level" theme becomes so representative of the series that it supplants the planned Main Theme in later games and advertising material. After all, chances are that people will spend more time on the first level learning the ropes rather than admiring the title screen. Since most developers are aware of this, they'll be likely to spend a little more time on the Level 1 music, and perhaps put it in a higher number of levels due to the extra work put into it, further feeding into this trope. This trope is more common in linear games (like platformers and shoot-em-ups) as opposed to Sandboxes or [=RPGs=], where level 1 is often either [[QuickSandBox not clearly defined]] or played after spending an appreciable amount of time on the TraversibleWorldMap.

A Sub-Trope of BootstrappedTheme. If sequels continue to use the level 1 music from the first game, it's also a form of FirstInstallmentWins.
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!!Straight Examples of this trope include:

* ''Franchise/SuperMarioBros'':
** [[http://www.youtube.com/watch?v=wGX4obVl64w "Ground Theme"]], also known as the Overworld theme. It's a well known example and the TropeCodifier.
** Averted in ''VideoGame/SuperMarioBros2''. The [[http://youtu.be/fqtKBlK3YII title theme]] was an arrangement of the [[http://youtu.be/TBx-8jqiGfA underwater theme]] from the original.
** Likewise, when ''VideoGame/SuperMarioAllStars'' gave each game their own title themes, they were all based on the underwater theme as well. In order, here are the ''All-Stars'' themes for the original ''[[http://youtu.be/ZBny76cJGgc Super Mario]]'', ''[[http://youtu.be/iE1U6iM1glA Lost Levels]]'' and ''[[http://youtu.be/Z9UmwpiCZZE 3]]''.
* ''Franchise/SonicTheHedgehog'': [[http://youtu.be/SF9ZLNxHaBY Green Hill Zone]]. The [[http://youtu.be/eQ9l1BsqvAo original title theme]] never appears these days unless as a throwback (such as the title screen in ''VideoGame/SonicGenerations'', itself a throwback to the whole series).
* ''Franchise/TheLegendOfZelda'': [[http://youtu.be/vGBVW2Yt1X4 Hyrule Overworld]].
* ''VideoGame/{{Kirby}}'': [[http://youtu.be/OCH6nQYflwY Green Greens]]
* ''VideoGame/{{F-Zero}}'': [[http://youtu.be/a0WzWdSVFmE Mute City]].
* ''VideoGame/KidIcarus'': [[http://youtu.be/NC0Hr9CrFRc Underworld]]. It has the same intro as [[http://youtu.be/p08wyrAYMrs the title screen music]], but the two themes differ from there.
* ''Franchise/{{Castlevania}}'': [[http://youtu.be/0AZ5XZHIDh0 Vampire Killer]].
** Also [[http://www.youtube.com/watch?v=EjazC45Qkww Bloody Tears]], the overworld theme for the second game.
** Also [[http://www.youtube.com/watch?v=78706bv98S8 Beginning]], the Level 1 theme for the third game. These three tunes are featured more than any others across the series. For example, in ''VideoGame/CastlevaniaJudgment'', they're used as the respective themes of Simon Belmont, Carmilla, and Trevor Belmont.
* ''VideoGame/{{Contra}}'': [[http://youtu.be/Tifv7qh_hmY Battle in the Jungle]], which is remixed in ''Contra: Shattered Soldier'' and ''Contra 4''.
* ''VideoGame/DonkeyKongCountry'': [[http://youtu.be/Ep9N-jFCht4 "DK Island Swing"]], also known as "Jungle Level", "Jungle Groove", or by its stage moniker, "Jungle Japes". Slightly unusual in that the music changes tone halfway through in the original game, due to it actually being a mashup of two different pieces, but only the first half is usually remembered.
* ''VideoGame/{{Metroid}}'': [[http://youtu.be/T-2sE0Napg0 Brinstar]]. They played with it in ''VideoGame/MetroidZeroMission''--in it, the item/save tunes are versions that sound far closer to the original game's, which has a different melodic focus than the versions that came from ''Super Metroid'' and on that gamers tend to be more familiar with. This is used to great effect when [[spoiler:Samus gets her power suit back after being shot down by the Space Pirates]], causing the modified later-game jingle to sound out, reorchestrated, in full force. [[https://www.youtube.com/watch?v=LhAQfpbsymU Theme of Super Metroid]] is also considered to be this by some, due to that entry's status as being the the best game in the franchise.
* ''VideoGame/{{Doom}}'': [[http://youtu.be/BSsfjHCFosw At Doom's Gate]] for the first game, [[http://www.youtube.com/watch?v=qURei6svd90 Running from Evil]] for the second.
** Arguably, the first levels of the first ''Doom'''s episodes could have this trope. Episode 2, ''At the Shores of Hell'' has [[http://www.youtube.com/watch?v=gVOXrgGJBJk I Sawed the Demons]]. Episode 3, ''Inferno'' has [[http://www.youtube.com/watch?v=j35Xak1O2lo Untitled]] and in ''The Ultimate Doom'', the first level of Episode 4, ''Thy Flesh Consumed'', has [[http://www.youtube.com/watch?v=FtlsH6RCH3k Sign of Evil]].
** From, ''Final Doom, TNT: Evilution'' has [[http://www.youtube.com/watch?v=wAi1q0LkTs4 Sadistic]], while its sister game ''The Plutonia Experiment'' has [[http://youtu.be/cBu0Iqlrunw The Imp's Song]].
* ''VideoGame/FinalFight'': [[http://youtu.be/AgJq48fcySk BGM 1]] was remixed as [[http://youtu.be/sy8VW_VXgOA Guy's theme]] in almost all of his fighting game appearances (starting with the original ''VideoGame/StreetFighterAlpha''), and also served as [[http://youtu.be/lqE-5y_q1dk Haggar's theme]] in ''VideoGame/MarvelVsCapcom3''.
* ''VideoGame/StarFox'': [[http://youtu.be/eclAC0JQJYk Corneria]].
* ''VideoGame/RType'': [[http://youtu.be/BaPU7Kej0oo R9, To the Front!]]
* ''VideoGame/GhostsNGoblins'': [[http://youtu.be/gA_e0QpVdLc Haunted Graveyard]], which was used as Arthur's theme for ''NamcoXCapcom'', ''MarvelVsCapcom3'' and ''VideoGame/ProjectXZone''. Also used as an alternate EasterEgg theme for [[BigBoosHaunt Shade Man's stage]] in ''VideoGame/{{Mega Man 7}}''.
* ''VideoGame/{{Raiden}}'': "Gallantry".
* ''VideoGame/{{Gradius}}'': "Challenger 1985", whose melody also appears in the intro to the Stage 2 music for ''Gradius V''.
* ''VideoGame/BlasterMaster'': [[http://youtu.be/y7L9KXVMSQs "Area 1 (Forest)"]]
* ''VideoGame/JourneyToSilius'': [[http://youtu.be/NjG2ZjPqzzE "Space Colony Ruins"]], which is better remembered than the [[http://youtu.be/jkWYvENgxwA title theme]] (although the former uses the same bassline as the latter in its refrain) and is reused for the [[BookEnds last stage]].
* The NES ''VideoGame/{{Batman|Sunsoft}}'' game's first stage theme is closely associated with the title and there are plenty of covers and remixes of the song, both because of its sheer coolness and because the NintendoHard nature of the game made it the most frequently heard tune for players.
* ''VideoGame/{{Valis}}'': [[https://www.youtube.com/watch?v=CPl24eXTZTA "Flash of Sword"]](Stage 1), although the series also has an official recurring title theme, [[https://www.youtube.com/watch?v=DM-D5TV0ND4 "Fantasm Soldier"]].
* ''VideoGame/MetalGear'': [[http://www.youtube.com/watch?v=xh8Odw3wQbE The Theme of Tara]], the main infiltration theme in the [=MSX2=] version, was later reused as [[http://youtu.be/2swZCYSRFt8 Metal Gear's theme]] in ''VisualNovel/{{Snatcher}}'', as well as the [[http://youtu.be/jW0BurBNB58 VR Training]] theme in ''VideoGame/MetalGearSolid'' and [[http://www.youtube.com/watch?v=RLRIn6NwbTI plays]] during Solid Snake's debut in the story mode of ''Super Smash Bros Brawl''.
* ''GanbareGoemon'': The [[http://www.youtube.com/watch?v=u5LxQvPVDmw Stage 1]] theme was remixed as the background music for [[http://www.youtube.com/watch?v=R45Wch50aYI Sundowner's Garden]] in ''VideoGame/MetalGearRisingRevengeance''.
* The opening section of ''VideoGame/DungeonSiege'' features music that seems to have been written with this idea in mind, as the name of that track is "Main Theme 1," and variations on the theme are used in places throughout the game, including during the FinalBattle and the credits. The FinalBattle theme was also carried over into the tutorial level for ''Dungeon Siege II''.
* ''DynamiteHeaddy'' uses a variation of the level 1 music as its title theme.
* While ''{{Ikaruga}}'' has a few songs to choose from, the level 1 music is especially infectious and the main part of it is used again near the end of the game. The only other recurring song is a tune that plays for three bosses, including the one in level 1.
* The Franchise/TalesSeries has several main battle themes for each game. However, most crossover games tend to feature the first battle themes of each game.
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!!Subversions, aversions, and inversions include:

* The ''VideoGame/BionicCommando'' theme appears to be a straight example, being the zone 1 music from the {{NES}} game but in the original arcade game the music is used on the second level.
* The ''VideoGame/MegaMan'' series is all over the place with this trope:
** ''VideoGame/MegaMan1'': Cut Man's theme is a straight example as it is usually the first level selected.
** Averted and subverted in ''VideoGame/MegaMan2'' where the title theme is used to represent Mega Man in ''VideoGame/MarvelVsCapcomClashOfTheSuperheroes'' and the other iconic theme is the first level... of the boss's fortress.
** The ''VideoGame/MegaManLegends'' subseries averts this by having The Flutter Vs. Gesellschaft theme from later in the game as the Iconic theme.
** The {{retraux}} [[http://youtu.be/TwbQi_G9cB0 advertisement]] for ''VideoGame/MegaMan10'' featured a cheesy jingle set to the tune of the opening stage of ''VideoGame/MegaManX'' of all things.
*** Most definitely [[JustifiedTrope justified]], since ''VideoGame/MegaMan10'' [[NotToBeConfusedWith could also be written as]] ''Mega Man X''.
** In ''VideoGame/ProjectXZone'', X's theme is that of ''VideoGame/{{Mega Man X4}}'s'' opening stage.
* ''VideoGame/DoubleDragon'': the title theme is played during [[ThemeMusicPowerUp the final boss battle]], but during the bonus sibling match that occurs when two players complete the game together, the music changes to the Mission 1 theme. This also holds true to the NES version, which has Machine Gun Willy as the [[DemotedToDragon penultimate boss]] and Jimmy Lee [[AdaptationalVillainy as the final boss]].
** The arcade version of ''Double Dragon II'' uses a BossRemix of the title theme in its penultimate battle (again with Willy), prior to the final battle with the [[MirrorBoss Lee clones]]. In the NES version, where Willy is absent, this remix plays during the tractor battle in Mission 6.
** ''Super Double Dragon'' has a different title theme and the classic Double Dragon Theme is instead used as background music for Mission 5. The Japanese version ([[MarketBasedTitle titled]] ''Return of Double Dragon'') restores the Double Dragon theme to its rightful place and uses an arranged version of the Mission 1 theme from the original arcade game for Mission 5.
* In ''DynastyWarriors 2'', the theme for the Battle of Hulao Gate, "[[http://www.youtube.com/watch?v=7k_kgBN3bA8 Jump Into the Battlefield]]", is extremely popular and well known, even though the Battle of Hulao Gate is the second stage in the game after the Yellow Turban Rebellion.
* ''{{VideoGame/MOTHER|1}}'': [[http://youtu.be/QYqDCPg7GPE "Pollyanna"]] is the overworld tune that plays at the start of the game when Ninten is the only party member. It is not considered the theme song for the game (that is usually either [[http://youtu.be/f5_R4WMBZjg the title screen theme]] or [[http://youtu.be/85XM_Nl7_oo Eight Melodies]]), but it is considered the theme for ''the {{VideoGame/MOTHER}} series as a whole''.
* NiGHTS plays with this trope. While the main character's theme, Dream Dreams, is considered the series' main theme, the first level's song, Paternal Horn, is treated as a secondary theme and is used in every SegaSuperstars game that features a [=NiGHTS=] level.
* ''AnarchyReigns'' has many {{Leitmotif}}s for its characters, but the theme that caught on most is Tre-Dot's ''[[http://www.youtube.com/watch?v=iqPT26AH940 Ruthless]]'', which was used as the first song in-game from the demo.
* Reversed in VideoGame/MegaManZero where the first level's theme was Zero's theme from the original X game.
** And on the topic of Zero ''MarvelVsCapcom3'' averts this by using the Copy Zero battle theme from X2.
* The [[BootstrappedTheme most famous song from]] {{Okami}} is [[http://youtu.be/ya3yxTbkh5s The Sun Rises]], played during the final battle. [[ThemeSongPowerUp There's a reason for that.]]
* The Stage 1 music in ''Shockman is'' the title theme.
* The theme most often associated with the ''VideoGame/SuperMarioGalaxy'' games is the Gusty Garden Galaxy theme, from a level in the ''middle'' of the first game (and bars of it are also heard in the Purple Coin stages, which are only available in the ''postgame''.)
* The first ''VideoGame/Wolfenstein3D''-based secret level in ''Doom II'', a recreation of ''[=Wolf3D=]'' [=E1M1=], uses [[http://www.youtube.com/watch?v=veJp8Qjcymo the music track from the final boss]] of ''Spear of Destiny'' rather than its original track.
* While the levels can be tackled in any order (moreso in the remake) the theme most associated with the ''VideoGame/DuckTales'' game is the music from the last level on the list, the Moon. The first level, the Amazon, is usually ignored (though Music/BrentalFloss did a lyrical version of both of them).
* ''VideoGame/DonkeyKongCountry 2's'' most iconic tune, ''Stickerbush Symphony'', is heard in the first quarter of the game rather than the beginning.
* Despite not generally having a consistent theme tune, the ''VideoGame/WarioLand'' series seems to avert this when it comes to what music's either the most memorable or remixed in later games. Wario Land 3's most remembered theme is the music box song played during the ending credits, and Wario Land 4's most remembered songs are the Crescent Moon Village theme (played during the first level of the Sapphire Passage and then in the first WarioWare game), the Palm Tree Paradise theme (first level of the Emerald Passage) and the Curious Factory theme (first level of the Ruby Passage and used as part of the Paper Plane song in WarioWare). The actual first level themes in both games are basically unknown to anyone who hasn't played it in the last year or so.
* The best-known music of ''VideoGame/{{Touhou}}'' are the boss themes (and their many, many, many, ''many'' remixes), which take some familiarity with the BulletHell genre to hear. The most iconic of them tend to be from the [[BonusBoss EX Stages]], at that, which are even harder to actually hear in-game.
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