My name is Jason D. Wittman, and I often browse at your Chess Variants website. I myself like to invent chess variants as a hobby (in fact, I sold one these to Steve Jackson Games, from whom it is sold commercially. It is called Tile Chess, and it is listed on your website).
I would like to inform you of another variant of my invention that you may find intriguing. I call it Knight Court, and I honestly believe that it is the smallest possible playable chess variant, for it is played on a 3 x 3 board.
I.e., the players start with a knight, bishop, and rook, in that order on their home row.There is no King in this game because the object is to checkmate the Knight (when I tried a 3 x 3 variant with the king as the royal piece, the game turned out to be one-sided). All the pieces move as in normal chess. Rules regarding check and checkmate that would normally apply to the king here apply to the knight.
Also, when a piece is captured, the owner of that piece may 'drop' that piece onto an empty square on any subsequent turn (this is like Shogi, except the pieces do not change owners. White pieces remain white and are dropped by the white player, and the same goes for Black). This means, of course, that capturing a piece is not always a good idea.
Important: it is illegal to move back and forth between the same positions (in other words, no draw by three-move repetition). Both players must vary their moves.
As mentioned above, a player wins the game by checkmating the opponent's knight.