If the game tree of crazyhouse (chess variant) if greater than the one in chess, why isn't Monte Carlo algorithm used for crazyhouse engines?
It has a great success in go (the board game) and I don't see why it would fail for crazyhouse.
One would simulate lots of random games from a given position, and then choose the move that leads to a higher win percentage. The advantage in crazyhouse over go for it is that in crazyhouse like in chess, it's extremely easy to check out who won the game. While in go even the top programs still do not count as well as the average player, for some position bots fail (even the 6 dan level bot "zen" on kgs go server) and thus may lead to innacurate moves.