IAGO Chess is unique in its nature. The best way to view IAGO Chess is a system used to manage the wide range of interests on the part of people who like to play, and an approach to acclimate new players to the system.
Because of this, you won't find one set of codified rules, as you would with other chess games. The IAGO Chess system accomplishes its objectives by the use of multiple versions (classes) of the game that represent the fullness of the chess experience. These versions build upon one another,
to allow a person to get fully familiar with the game. There are six versions (classes) of the game. These versions are: A-Class, B-Class, C-Class, M-Class, V-Class, and X-Class.

This version of chess is more than just a chess variant, it is a system by which chess can integrate variants and evolve. It has multiple layers and is robust enough to change over time. Its mission is to be a forever evolving version of chess that will provide a migration path for changes.

It is also meant as a framework for playing all versions of chess relating to the International Abstract Games Organization.

For the actual rules, check out the Chess Variants website:
http://www.chessvariants.org/index/msdisplay.php?itemid=MSiagochesssyste

Zillions adaptation of the game is here:
http://www.zillionsofgames.com/cgi-bin/zilligames/submissions.cgi/65274?do=show;id=1576

This contains B, C, M and V-Class versions of the game, that is part of the IAGO Chess System.