I found this because you've been a firm favourite of mine since Hanna in a Choppa, and I'm shocked that a game like this from someone with your pedigree hasn't blown up and hit the front page yet. A very fun game with some very interesting challenges in the later levels.
Maybe you would consider allowing players to ratchet up the AI difficulty a little? It's a bit… dumb sometimes, occasionally missing the obvious killer move, which makes it far too easy to boldly stride into the fray and start decimating your opponent. If it's minimax, maybe consider a setting to let it look a couple ply deeper? The branching factor can get pretty high mid-game in some of the larger levels, but given how multiplying will naturally strand a few pieces, it probably doesn't get too bad… or does it? (Alternatively, you might be keeping that back for the app version of the game, in which case: I guess that works, because I'm kinda interested in buying it now. :P )
Oh, and the "pi pi eeeeeee" refrain at the end of each level earned me a few awkward over-the-shoulder looks from my husband. Did you really mean to make it *that* creepy?!
Anyway, another great game from a great developer. Keep up the good work, CMU; I look forward to seeing more from you!