Below is how download.com describes YeaChess:
Playing chess against a computer is supposed to be Mr. Spock's territory, but there's nothing stopping you from pitting your skills against a cybernetic opponent, thanks to Yea Chess by Drazen Beljan. It's a free chess-playing program that uses artificial intelligence and your computer's processing power to test your chess-playing ability at various skill levels.
Yea Chess is portable freeware that requires no installation; you can copy it to a USB stick or other portable device and always have access to your saved games.
Yea Chess not only gives you a challenging match but also helps you refine your game. It's easy to use and fun, too, if you don't mind losing a lot!
To download directly from CNET download.com, please follow this link http://download.cnet.com/Yea-Chess/3000-18516_4-10915788.html