ABC chess is played on a normal 8x8 chessboard. Each side has an army composed of a King, 8 Pawns, and 7 other pieces.
Imagine three different pieces whose moves do not overlap. Call these pieces A, B, and C. Now let there be three pieces whose moves are a combination of a pair of A, B, and C above. Call these pieces AB, AC, and BC. Now let there be a piece whose moves are a combination of all three pieces A, B, and C. Call this piece ABC.
Set up white pieces from a1 to h1 as follows:
Set up the white pawns on a2 through h2. Set up the black pieces to mirror white's pieces.
a1 b1 c1 d1 e1 f1 g1 h1 ABC BC AC C K A B AB
ABC Chess game is played by rules of International Chess, except for the pieces and some slight modifications to the special rules.
Obviously, in theory, any set of ABC pieces ought to be approximately equal in value to any other set having a similar net value of A+B+C. An ABC army will have a total mobility value equal to 4x(A+B+C). This means that an ABC army will be approximately equal to the mobility of the regular chess army when A+B+C = 31/4 = 7.75.
(Note that in the following list many pieces are defined using Ralph Betza's funny notation.)
Army Component A Component B Component C Army #1 Bishop Knight Wazir Army #2 Rook Alfil Ferz Army #3
Roc (FmJ) Chimera (WmL) Manticore (DmAmG) Army #4
Bowman (mWcB) Musketeer (mFcR) Lancer (mNcfbN) Army #5
Ferz Knight WD Army #6
Stormtrooper (Single-Step Rhino) Stuka (Dabbabah) Panzer (F2) Army #7
Ferz VLeaper  Ski-Bishop  Army #8 Falcon/Y-Rider (fBbR) Knight Ballista (fRbF)
 The VLeaper jumps two squares orthogonally, then may step one square diagonally outward if the square first landed in is empty.
 The Ski-Bishop moves like a regular Bishop, except that it leaps over the first square travelled over. See George Jelliss' page A Guide to Variant Chess for further details.
This game was conceived as an alternate armies variant. The players are free to choose any ABC combinations mutually agreed upon as being equal in strength. More adventurous players can pit an ABC army against one of the already existing alternate armies, such as those extensively tested by Ralph Betza and friends. The example armies above are in the right ballpark for that, although not finely balanced. Feedback is welcome.
Veteran variant players will have no problem coming up with a suitable set of pieces. For those who have an Omega Chess set, the following piece representation can be used:
Players with painted figurines can use a different figurine for each piece. Players with no imagination can simply stick letters on checkers.A = Bishop B = Knight C = Rook AB = Wizard AC = Queen BC = Champion ABC = Inverted Rook
An implementation of ABC Chess has been written for Zillions of games. You can download it here: