Will do if I make a proper post-jam version. In the very limited play testing I did, it wasn't an issue, but it seems a few people have had difficulty on the first few levels. Until then, I'll explain it here:
Any character you're not controlling cannot move, and is counted as being on the other team in term of movement. If you capture a piece, your current piece will swap places with it, and you will now be controlling the piece you just captured.
(The whole swapping places thing is a bit weird, I know, but its absolutely chessessary to make good puzzles, I've tried)