The Gigachess OST just hit Steam, check it out!
http://store.steampowered.com/app/604890/
The soundtrack will be added to your Steam music library for listening through the Steam client's media player, and if you'd like to access the files directly, just navigate to the Gigachess folder in your Steam games directory (likely to be C:\Program Files (x86)\Steam\steamapps\common\Gigachess\Gigachess OST for a typical installation).
Alternately, the tracks are all up on the Gigatross Games Soundcloud for easy streaming! :D https://soundcloud.com/gigatross-games/sets/gigachess-ost
Thanks for playing (and listening to!) Gigachess <3