For chessup2, I believe adding variants to the board could be enjoyable; naturally, only certain options would function well. Racing kings, king of the hill, giveaway, atomic, Chess960, and 3 Check seem possible, though others may exist. In some modes, the king must reach a zone, which could be subtly highlighted in blue or green. For players unfamiliar with the setup, a QR code on the screen might link to a page showing piece placement and instructions for each mode.
YESS letts do it!