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 not clearly defined
or played after spending an appreciable amount of time on the Traversible World Map
A Sub-Trope of Bootstrapped Theme
. If sequels continue to use the level 1 music from the first game, it's also a form of First Installment Wins
Straight Examples of this trope include:
- Super Mario Bros.:
- Sonic the Hedgehog: Green Hill Zone. The original title theme never appears these days unless as a throwback (such as the title screen in Sonic Generations, itself a throwback to the whole series).
- The Legend of Zelda: Hyrule Overworld.
- Kirby: Green Greens
- F-Zero: Mute City.
- Kid Icarus: Underworld. It has the same intro as the title screen music, but the two themes differ from there.
- Castlevania: Vampire Killer.
- Also Bloody Tears, the overworld theme for the second game.
- Also Beginning, the Level 1 theme for the third game. These three tunes are featured more than any others across the series. For example, in Castlevania Judgment, they're used as the respective themes of Simon Belmont, Carmilla, and Trevor Belmont.
- Contra: Battle in the Jungle, which is remixed in Contra: Shattered Soldier and Contra 4.
- Donkey Kong Country: "DK Island Swing", also known as "Jungle Level", "Jungle Groove", or by the name of its rearrangement for Donkey Kong 64, "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.
- Metroid: Brinstar. They played with it in Metroid Zero Mission—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 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. 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.
- Doom: At Doom's Gate for the first game, 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 I Sawed the Demons. Episode 3, Inferno has Untitled and in The Ultimate Doom, the first level of Episode 4, Thy Flesh Consumed, has Sign of Evil.
- From, Final Doom, TNT: Evilution has Sadistic, while its sister game The Plutonia Experiment has The Imp's Song.
- Final Fight: BGM 1 was remixed as Guy's theme in almost all of his fighting game appearances (starting with the original Street Fighter Alpha), and also served as Haggar's theme in Marvel vs. Capcom 3.
- Star Fox: Corneria.
- R-Type: R9, To the Front!
- Ghosts N Goblins: Haunted Graveyard, which was used as Arthur's theme for Namco × Capcom, Marvel vs. Capcom 3 and Project X Zone. Also used as an alternate Easter Egg theme for Shade Man's stage in Mega Man 7.
- Raiden: "Gallantry".
- Gradius: "Challenger 1985", whose melody also appears in the intro to the Stage 2 music for Gradius V.
- Blaster Master: "Area 1 (Forest)"
- Journey To Silius: "Space Colony Ruins", which is better remembered than the title theme (although the former uses the same bassline as the latter in its refrain) and is reused for the last stage.
- The NES Batman 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 Nintendo Hard nature of the game made it the most frequently heard tune for players.
- Valis: "Flash of Sword"(Stage 1), although the series also has an official recurring title theme, "Fantasm Soldier".
- Metal Gear: The Theme of Tara, the main infiltration theme in the MSX2 version, was later reused as Metal Gear's theme in Snatcher, as well as the VR Training theme in Metal Gear Solid and plays during Solid Snake's debut in the story mode of Super Smash Bros Brawl.
- Ganbare Goemon: The Stage 1 theme was remixed as the background music for Sundowner's Garden in Metal Gear Rising: Revengeance.
- The opening section of Dungeon Siege 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 Final Battle and the credits. The Final Battle theme was also carried over into the tutorial level for Dungeon Siege II.
- Dynamite Headdy 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 Tales Series has several main battle themes for each game. However, most crossover games tend to feature the first battle themes of each game.
- Rad Racer: BGM 1, AKA Sunset Coastline.
Subversions, aversions, and inversions include:
- The Bionic Commando 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 Mega Man series is all over the place with this trope:
- Double Dragon: the title theme is played during 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 penultimate boss and Jimmy Lee as the final boss.
- The arcade version of Double Dragon II uses a Boss Remix of the title theme in its penultimate battle (again with Willy), prior to the final battle with the 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 (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 Dynasty Warriors 2, the theme for the Battle of Hulao Gate, "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.
- MOTHER: "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 the title screen theme or Eight Melodies), but it is considered the theme for the 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 Sega Superstars game that features a NiGHTS level.
- Anarchy Reigns has many Leitmotifs for its characters, but the theme that caught on most is Tre-Dot's Ruthless, which was used as the first song in-game from the demo.
- Reversed in Mega Man Zero where the first level's theme was Zero's theme from the original X game.
- And on the topic of Zero Marvel vs. Capcom 3 averts this by using the Copy Zero battle theme from X2.
- The most famous song from Ōkami is The Sun Rises, played during the final battle. There's a reason for that.
- The Stage 1 music in Shockman is the title theme.
- The theme most often associated with the Super Mario Galaxy 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 Wolfenstein 3D-based secret level in Doom II, a recreation of Wolf3D E1M1, uses 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 DuckTales game is the music from the last level on the list, the Moon. The first level, the Amazon, is usually ignored (though Brental Floss did a lyrical version of both of them).
- Donkey Kong Country 2's most iconic tune, Stickerbush Symphony, is first heard about a third of the way through the game rather than at the beginning. (In fact, the first level's theme is a remix of the final boss music from DKC1.)
- Despite not generally having a consistent theme tune, the Wario Land series seems to avert this when it comes to what music's either the most memorable or remixed in later games. Although both Wario Land: Super Mario Land 3 and Wario Land II share the same main theme, none of the other games do. The most remembered theme from Wario Land 3 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 Touhou are the boss themes (and their many, many, many, many remixes), which take some familiarity with the Bullet Hell genre to hear. The most iconic of them tend to be from the EX Stages, at that, which are even harder to actually hear in-game.