Well I finished the game. It was fun experience, although the fact that there is no rest and it just forces you in to fight makes it a bit boring. Having some kind of a trader of store would be good way to get ride of some items and get what you want.
I found a bug, If I'll click to many times on 'new game' before game actually started, slimes will stuck and tutorial will never start and there'll be no way to exit.
Reading one of comments, I can suggest to explain tutorial over several different battle. first explain how to attack and defend, when you'll get your first items after that explain how to use them and so on.