Boss-Only Level

A level that consists entirely of a Boss Battle. Usually, this is done for plot reasons, even in games which don't have much. Said boss is almost always the penultimate or final boss.

This trope has become increasingly more common in recent platformer games with (slightly) more deeper plots.

When taken to extremes this leads to a Boss Game, where every level is a Boss-Only Level. Compare Boss Rush, which is a level devoted to several previously-fought bosses.

Action Game

 * Almost all of the bosses in the first American McGee's Alice are like this. Only the Red King and Tweedle Dee and Tweedle Dum avert this.
 * Mission 6 in Contra: Shattered Soldier is entirely a Sequential Boss fight, and Mission 7 is the True Final Boss.

Action Adventure

 * The final level of the original Ecco the Dolphin is devoted to the battle with the Vortex Queen.
 * Ecco: The Tides of Time also has a Vortex Queen level, though it's not the final one.
 * In the Playstation Spider-Man game, the chapter "Rhino's Rampage" consisted solely of a boss fight with Rhino.
 * Most (if not all) of Bomberman's boss fights were in Boss-Only Levels.

Beat'Em Up

 * Bayonetta does this with the Four Cardinal Virtues (similar to the Seven Heavenly Virtues...but as angelic monsters), although one of them has a few enemies before the boss fight.
 * This often features on final stages in Devil May Cry.

Fighting Game

 * Super Smash Bros. Brawl does this in the Adventure Mode, with "The Ruined Hall" and "Battleship Halberd Bridge". "The Canyon" can be considered a variation, since the level only contains a Multi Mook Melee.

First-Person Shooter
""It's down to you and me, you one-eyed freak!""
 * The only opponent in Episode 1 Level 9 of Wolfenstein 3D was the boss, Hans Grosse.
 * The Sky Temple in Metroid Prime 2: Echoes, as well as the Leviathan Seed regions in Metroid Prime 3: Corruption. These are a first for the Metroid series, as the bosses often reside at the end (or central part) of large zones.
 * The Tower of Babel (a fight against the Cyberdemon) and Dis (Spider Mastermind) from Doom.
 * The Lair of Chthon from the original Quake I. No points for guessing what boss you fight in there.
 * The Stadium, the last level of episode three in Duke Nukem 3D; a duel against the Cycloid Emperor on a football stadium.


 * The final level in Batman Doom, featuring a duel against Bane in.

Hack and Slash

 * Exaggerated in Gauntlet Dark Legacy: each of the realm bosses gets a level to themselves.
 * The Rank 10 and 7 stages in No More Heroes 2 Desperate Struggle.

Platform Game

 * The Sonic the Hedgehog series loves this trope. The trend started with the first game (which has the Final Zone), and really took off after The Doomsday Zone, with the final bosses of most games take up their own level, usually played while in Super Mode.
 * Exaggerated in pretty much every Sonic game since Adventure, which all give bosses their own levels.
 * The first Super Mario Galaxy has Bonefin Galaxy.
 * Boss Blitz Galaxy in Super Mario Galaxy 2. Also a case of Boss Rush.
 * In Mega Man X 4, the duel against Colonel is one of these if you're playing as X. (If you're playing as Zero, you get a cutscene instead.)
 * Played With in the first Mario vs. Donkey Kong: while clearing the Mini-Mario Levels always leads players to facing Donkey Kong, after the first battle in any given world the Boss Battle itself is freely accessible afterwards, although not going through the MM levels first "punishes" the player with four Hit Points instead of the "usual" six, as it would be the case if all six Mini Marios are rescued.
 * The sequels play it straighter.
 * In the original Crash Bandicoot trilogy, bosses have their own separate levels, presumably in order to avoid Boss Dissonance. It worked.
 * The original Spyro the Dragon trilogy did this as well.
 * The final boss of Wario Land 3 is this.
 * All the bosses of 4 as well.
 * In Wario World, while there are bosses at the end of actual levels, world bosses are contained in their own level.
 * Donkey Kong:
 * The bosses in Donkey Kong Country Returns, with the exception of the final one, are housed in otherwise empty levels.
 * Indeed, the original Donkey Kong Country trilogy did the same.
 * In Castlevania for the NES, stage 12 is a short corridor leading to a Boss Battle, and stage 18 is the famous stairs leading up to an antechamber to the Final Boss room. The MSX2 version turns these into considerably longer levels.
 * The eighth level of Kid Niki: Radical Ninja is mostly just the second part of the Final Boss battle, where he starts running away.
 * The penultimate and/or final stage of Wily's Castle in the Mega Man series is usually this.
 * Exaggerated in Mischief Makers, every boss has their own stage. Mini-bosses have their own stages!

Role-Playing Game

 * In Freedom Force, the last battle against Time Master is just him and his time clones.
 * Dark Cloud does this with most of its boss fights.
 * Final Fantasy IX features the Hill of Despair, where you fight the final boss, Necron.

Shoot'Em Up

 * Famously, the third level of R-Type is essentially one long battle against a giant alien spacecraft.
 * Gundemonium Series Recollection and Gundeadli Gne do this in their final levels.
 * Zone M/Titanic Lance in Darius Gaiden. Special in that Zone M is right in the middle of the game, and Titanic Lance is generally agreed to be harder than most of the final bosses.
 * The first Bangai-O game has the duel with Sabu in level 26. There are no enemies at all, with the only obstacles being falling block generators.

Simulation Game

 * The final mission of Ace Combat Zero: The Belkan War is just one extended Sequential Boss battle that still takes longer to beat than a typical campaign mission.

Third-Person Shooter

 * The final level of Kid Icarus Uprising is a long, multi-stage boss fight.