Gary seems to sometimes use a character's last move card for no apparent reason, leaving himself open to lava, acid, etc. And occasionally when he's on a damaging terrain modifier, he won't use the move cards he has. Anyone else notice this?
Yeah, I've noted occasions when the AI decides to use a move card and then decides not to actually move anywhere or even to change facing. It's like whatever algorithm is used to decide what card to play next doesn't actually take into account whether there's a better square available to move to. This is actually a known feature. The devs have mentioned that the AI often passes at random times in order to make the AI less predictable and a bit harder to take advantage of. Without those random passes, it would be even easier to make the AI waste its moves in order to use lava against it. Of course its not perfect this way either as the AI will often pass instead of moving away from lava, delivering the finishing blow or capturing the important VP square.
I get the impression that it's scripted so that certain types of enemies do not understand terrain and others do. I.e. Gary is trying to be a good GM rather than trying to kill the party at all costs (as Melvin would!)