Tracked music is compatible with most PC and Amiga players. Most popular in 1987-1997, on Amiga and PC, arrangements have been released mostly until 1999.

Common Platforms: Amiga, PC Dos, PC Windows, Amiga CD32 + Arranged/remixed tunes on all other platforms
Common file types: MOD / XM / S3M / IT
Game Music Base Icon:

Where to download tunes

World of game mods - your absolute solution if you're looking for game MODs
UnExoticA - Site dedicated to Amiga's game music, and you will find many Amiga game MODs there.
Rpgamer - This site is realy good source of anything for roleplaying games (RPGs) and above all they've very big collection of tracked videogame arrangements and remixes.
SSTrax - This page should be dedicated to all tracked remixes of console/computer tunes, but unfortunately till now it isn't up. Good thing is, that I have most of their archive downloaded and available from here :)
Back to the Roots - Really must-visit for all Amiga's freaks - games, music, database of titles and much much more!
AMI Sector One Network - Another nice Amiga's site that has the similar type of contents as Back to the roots, so it's various Amiga's stuff including game music
Amiga Soundtracks - Amiga page with many game tunes, nice thing is that only mod tunes are there (not exotic formats).
X-Treme Game Music - Only the best game music in various formats (Midis, Mods, SPCs etc..)
AmigaRemix - MP3 remixes of great old Amiga Tracked tunes.

Some more thoughts

MOD is the main music format for Amiga, and Amiga musicians did really great tunes on this format. Here I must mention Bjorn Lynne (known as Dr. Awesome), who firstly released tunes for demos, then he moved onto game music, to release high quality work on Project X, Alien Breed 3D or Worms. Later he made into Digital Audio sphere, to release great quality CD soundtracks. Another one of the best Amiga musicians, Allister Brimble, was master of various music styles - either great childish happy tunes as in Wonderland, Superfrog or Troddlers games, or "respected" tunes as Alien Breed, or part of Project X tunes. Real master of "chip"-music was Matthew Simmonds, aka 4-Mat, he made very nice tunes to Codemasters' Dizzy games, Core Design's Chuck Rock and much more. And last-but-not-least, "swedish god" Olof Gustaffson. He hasn't sounded many games, but what he did, it was really "much depended" on sound. You remember Pinball Dreams, Pinball Fantasies and Pinball Illusions? Yes, this man did great job there! And in my opinion best of the best have been been Benefactor tunes. This great "Lemmings-logical" game is really proud of its sound... On PC have been released in Tracked format (mostly S3M or IT) around 5% of tunes in years between 1995-2000. The most famous are Unreal, Unreal Tournament, Deus Ex, Age of Wonders etc. Also very big amount of re-arranged music is stored in some of the tracked formats, though now the former trackers mostly create MP3 arrangements.
The MOD format is supported by most Windows players such as WinAmp etc., but they're often emulating these MOD tunes with questionable quality. If you really want to listen to MODs with "original" Amiga's feeling under Windows, download ModPlug player (see links to software below). The bad thing is, that not all Amiga tunes are in MOD format. In MOD format is only approx. 50% of all released Amiga game music and 90% of all released demo music. The rest is stored in Amiga Exotic formats.

Players and other useful links

Game Mods FAQ - Answered many questions about game mods, which player to use, what are they about etc.
ModPlug player - The best player to play MOD format music
DeliPlayer - This player plays most of the exotic music formats on PC, is also very good for MODs and MP3s too!
AstorPlayer - If you have Pocket PC, you can listen to MODs also on your boring travelling ways :) This program is very little, but has everything the good MOD player should have, including ZIP and RAR support for playlists!