I meant to put in a tiny help screen before the game starts, but I ended spending the last minutes of the jam trying to figure out that I needed to upload more than just the .exe file.
It's not that big problem I think. Because I figured it out by my self at the end. But maybe it helps if you just put a picture on your game page which says that you attack with the opening. (Reminds me also of the mouth of pacman :D)