The ultimate game sounds list is a large list of links that points to game soundtracks, game sound resources, and other related resources and downloads.

Music plays an essential part in most computer games, and good music is very memorable. I still remember all-time favorite tunes from the Last Ninja 2 on the C-64, the very relaxing Aquatic Ambiance tune of Donkey Kong Country on the SNES, the Cannon Fodder intro track and the soundtrack of The Secret of Monkey Island on the Amiga.

The resource listing below is grouped into three parts: Game soundtracks released by companies, resources like music databases, and misc resources.

Full game soundtracks released by game companies or rights holders.

Bioshock Soundtrack -- 2K games released the official Bioshock soundtrack.

Epic Games -- Epic Games released individual tracks and OST on SoundCloud.

Half-Life Orange Box Soundtrack -- The Steam game demo of Audiosurf comes with the full Orange Box Soundtrack. You find it under steamapps/common/audiosurf after installation of the demo.

Mass Effect 3 Extended Cut -- The soundtrack of Mass Effect 3. Requires login.

Sierra Game Soundtracks -- The archive offers soundtracks and theme songs of various Sierra games including Gabriel Knight, Leisure Suit Larry, Policy Quest, King's Quest, and others.

Stalker Soundtrack -- The official soundtrack CD of the game Stalker, as well as fan made music.

Tomb Raider Soundtrack -- Download various Tomb Raider soundtracks from this fan site.

Warcraft 3: Reign of Chaos Soundtrack -- Download the full Warcraft 3 Reign of Chaos soundtrack.

World of Goo Soundtrack -- Soundtrack is available in various formats including
FLAC.

Resources

The following sites host or index computer music.

A Game Music Index -- Covers C-64, NES and NES music.

ASMA -- The Atari SAP Music Archive is the Internet's largest Atari XL and XE music archive.

GSF Central -- Gameboy Advance music archive.

High Voltage Sid Collection -- Probably the biggest collection of C-64 Sid music.

Khinsider -- A huge resource for all things computer music. Features soundtracks, game rips and individual tracks for all kinds of systems. Game titles include Tony Hawks Pro Skater, Uncharted, Zelda, Kingdom Hearts, Harvest Moon and hundreds of others. Total size of collection is 1521 Gigabytes at the time of writing.

USF -- The Nintendo Ultra 64 Sound Format archive.

OCRemix -- Site that features remixes of popular computer, arcade and console games.

Project 2612 -- A side dedicated to Sega Genesis / Mega Drive music.

Remix.Kwed.Org -- A repository for C-64 Sid music.

RetroTracks -- Big collection of 8-bit, 16-bit and 32-bit classic video game music.

SNDH -- Collection of Atari ST music.

SNES Music -- A site dedicated to the Super Nintendo / Super Famicom.

Stone Oakvalley's Amiga Music Collection -- Hosts more than 120,000 different Amiga tracks.

The Mod Archive -- Large site hosting Amiga music. Torrent downloads available.

VGMusic -- The Video Game Music Archive hosts midi files of classic and modern consoles and computer systems.

VGMRips -- A site dedicated to retro video game music rips.

Zophar's Music Domain -- Hosts a lot of game music rips for classic systems such as the NES, SNES, Playstation or Sega Genesis

Misc

Bill Brown's website -- Offers music composed by the artist. Games include Quake II and III, Rainbow Six, Lineage, Return to Castle Wolfenstein and others.

MicroMusic -- The site is all about chiptunes.

Reddit GameMusic -- A subreddit dedicated to game music (mostly videos on YouTube).

Spotify -- Spotify is home to a large number of video game soundtracks.

YouTube -- You find plenty of soundtracks on YouTube. There is no central location for those however, but searches like "game title" soundtrack usually find these quickly.