Option Chess

Note: This variant is invented by Paul Bonham. This article describes the rules in a shorter way.

Rules

Play is mainly as FIDE chess. Play then proceeds as follows:

1. Players start with no double move tokens.
2. After Black's eighth move, both players are given twelve double move tokens.
3. After Black's forty-eighth move, both players are given an additional four double move tokens.
4. Number of double move tokens each player has is public information.
5. If you want to make a double move, you must put aside one of your tokens so that your opponent is notified of such thing (and they must be within view to notify such thing; this is so that you cannot make a single move and then push the clock while opponent's doesn't see and make a second move).
6. After both moves are made, you throw out the token to indicate the move is complete.
7. The first move of a double move is not allowed to give check or to capture.
8. If you make a double move while in check, you can get out of check on either the first or second move.
9. You are allowed to move the same piece twice in one turn, but if doing so, you cannot capture at all.
10. If your opponent has just moved one piece twice, you are allowed to capture it on the square it landed on at first (similar to "en passant").
11. Castling is still allowed, and counts as a single move.

Notes

Please see external link for more information: Option Chess by Paul Bonham | Chess News