I like it :)
Having different slimes with more predictable paths would be cool, like thin blue slimes that charged up for a line attack or fat slow slimes that moved like a knight in chess or perhaps jumped over squares etc.
I think I'd prefer it so you can hold down the wasd keys to move as after a while i got tired spamming the keys to move each tile haha.
I think it's a pretty cool idea and one that could be built up on. Nice job!