Game Soundtracks by Jon Sneyers makes it very easy to listen to soundtracks of games, which you might have already installed. A pre-installed audio player such as DeaDBeeF or Audiorace is required.

The following 73 games are recognized:

A Midsummer Day’s Resonance, A Winter’s Tale, AAAA, Amoebax, Angry Drunken Dwarves, Aquaria, ASCIIpOrtal, Barbie Seahorse Adventures, Battle For Wesnoth 1.10.x / 1.11.x, Biniax2, Blob Wars: Metal Blob Solid, BrainParty, CromoZome, Cube Trains, Digital: A Love Story, don’t take it personally, babe, it just ain’t your story, EarthInvasion, Endgame: Singularity, Exobius0, FLAT, freedroid-1.0.2, Frogatto, Frozen Fruits, Frozen-Bubble, Galactic Artifact, GCompris, Greyout, Gweled, Hex-A-Hop, Hexgem, Hurrican, I Have No Tomatoes, Jump Gunnar Jump, KAMI RETRO, LemmingsSDL, Lolicopocalypse, May Sky, MeAndMyShadow, Meritous, Microbes, Moonshine, Narcissu, NubNub!, PandoraPanic!, Penguin Command, pewpew2, Polly-B-Gone, PopStar, Pushover, Puzzletube, pydance, Race into Space, Rescue, RickyD, Rockbot, Rockdodger, Shunned Survivor, Spacejunk, Sudo Science, Super Geometry Dust, Super Hexagon, SuperTux, SuperTuxKart, Tapan Kaikki Bloodshed, The Devil, Tong, vGolf, Wars: Commando, Widelands, wizznic, Xmoto, Znax, Zoid’s Quest.

http://repo.openpandora.org/?page=detail&app=game_soundtrack.wb