An indie game type rising in popularity lately. Very similar to Rhythm Games in that every level is a music track, it is nonetheless different. A Rhythm Game is a specific genre, with tracks already charted beforehand. A Music Player Game can be of any genre, but the levels are generated procedurally from the music you feed it, typically the more intensive and loud the music, the more action you are going to see.
As a general rule, games that try to capture the mood of the music fare better than ones that try to follow the rhythm of the music. Currently, even the best software just doesn't work as intended for capturing the beat and melody a lot of songs, particularly those with subtly changing tempo and\or complicated layering. What it can do much more effectively is spot the "highs" and "lows" of a given song. Audiosurf is a prime example of a game that tries both and fares more consistently on the mood side (fortunately, the gameplay style suits the occasional rhythm-related shortcoming just fine).
A very common thing in these games is an online scoreboard, with every song having its own — the most popular tracks, obviously, offering the strongest competition.
- Audiosurf is the game that started the recent craze as well as made online scoreboards for each song — a Match-Three Game with some karting elements thrown in. Being sold on Steam also helped.
- Beat Hazard: a Bullet Hell/seizure simulator where the aggressiveness of enemies and the strength of your weapon depend on the song.
- Crypt Of The Necrodancer is half this, half roguelike.
- 1...2...3...Kick It! (Drop That Beat Like an Ugly Baby) is Aaaaaaaaaaaaaaaaaaaaaaaaa A Reckless Disregard For Gravity but with level generation.
- Dance Factory is a Dance Dance Revolution clone with automatic charting.
- There was a very old Tiger Electronics handheld game called M.A.G.S.. The point of the game was to shoot at these little bars of red lights before a they hit the barrier. It was very fun but it's super obscure and hard to find.
- Melody's Escape
- Music Catch is an indie game that was originally just a flash game. Then it was made downloadable and you could play any track you wanted on it. The goal was to "catch" the blue music notes that came out and avoid the red notes. The purple notes added to your multiplier. A sequel was released in 2010 with more variations but you lost the ability to play any track you wanted to.
- Phaze was a game for spin-wheel iPods that allowed you to play any track you loaded onto your device. It was very close to Guitar Hero in concept. It's unfortunately unavailable on iTunes download, so Keep Circulating the Tapes.
- The Polynomial: Space of the Music
- Rhythm Zone
- Space Invaders Infinity Gene has a game mode where it reads off any music you have stored in your system and generates a stage based on it.
- Vector Stunt
- Vib-Ribbon is the Ur-Example.