I love it! Definitely my favorite GMTK game so far (although that may just be because this is the first puzzle game I've hit upon).
It was not clear at first that the number on my die needed to be higher than the other die when I take the other die's position, not when I'm next to the other die. A tutorial section could help clear this up. Or a level that demonstrates the mechanic in a way that would have cleared up my misunderstanding without needing words.
Like, a level where the obvious move is to go straight for the other die, which puts a high number on top when you're next to it, but puts a low number on the side facing away from it, so you can't attack successfully. But once the player tries that and fails, they'll see that the only other thing they can do is to go around a corner and attack from a different direction, which puts a low number on top when they're next to the other die, but a high number facing away from it, and allows them to win.
But I do like how the attack mechanic plus the fixed camera angle force the player to keep track of their die's orientation when they need to attack from the far side of a die. That's fun!
My only complaints are that sometimes my inputs got eaten if I hit the arrow keys too quickly, and it was sometimes hard to remember whether 'up' on my keyboard meant 'up-left' or 'up-right'. But those are both minor issues, and could be easily solved.
(also, for some reason, this doesn't run in Safari on OSX, but it works fine in Chrome)