This game is great. I love the blend of action and puzzle, where you can either be smart or quick. It's nice that it's mostly grid based, since the ghost snapping to the grid (and the bullets being grid aligned) gives me confidence in that it'll block the walls of bullets I'm rushing into. It's also great that the ghost's normal movement is not grid based, since that lends itself to better action gameplay. The difficulty is just right, too.
Minor nit-pick is that I think it'd be more intuitive to control if the ghost stayed in place when scrolling the screen and not moving the mouse. It's not like the ghost is synced-up to the mouse cursor anyway, since it gets stuck on objects.
I would play a full game of this.