Semi-Random Baseline Chess

(wild style 1 on Free Internet Chess Servers)

  White and Black play with piece arrangement, where each side's pieces are shuffled separately at random subject to two constraints:

  (1) because castling is such a big part of the game and adds so much more to planning ("I'll provoke a2-a3 so they won't castle queen's-side") the possibility of castling on either side should be preserved. After that, the pieces are randomly shuffled, subject to
(2) there being bishops of either colour square.

  This yields (I think) 18 different starting arrays, as follows: