Link to: R-Chess

R-Chess ("R" for "Reserve") is a variation of Crazyhouse. Whenever a player captures a piece it goes to his reserve, changing color, so that it now belongs to him. The difference to Crazyhouse is that pieces, with exception to pawns, must be recruited as reinforcement before being droped. This changes game dynamics a lot, since now pieces can be returned to board, but at the cost of iniciative. Sometimes positions will be simplified, sometimes not. On board maneuver will be more valorized, but drops will still have an important role. Pawns may not be dropped on the last three ranks, and promoted Pawns turn back into Pawns when they are captured. The pawns rank was moved one row to the front in order to give pieces space for defensive maneuvers, like in Shogi. The original idea was to shuffle the initial position like in Random chess in order to avoid all kind of theory (opening or endgame), but castle rules are not yet implemented.

R-Chess: http://www.zillions-of-games.com/cgi-bin/zilligames/submissions.cgi/57727?do=show;id=762