The inability to attack upwards or downwards is inconvenient. Also, the beginning of the game is very drawn out; perhaps the game's difficulty shouldn't be tied to the level, that would have created a dynamic early on. After a couple of upgrades, it's already playing quite well. I also noticed that the active abilities have too long a cooldown for me, at least 30 seconds for the blue head. I also think they should have added some level-specific healing.