Very good learning curve, I really liked how the game adds new mechanic with every level at the beginning :D but after a few levels it gets too hardcore - the level with three mouse cannons, two laser rats and three boxing rats is the overkill x) I quitted on that level. Mouse cannons have too big area of damage in my opinion, it is very hard to dodge them. But overall, the design of this game is captivating ;) and, at the beginning, positively challenging, but unfortunately not for the whole game