I managed to beat all four levels! You mentioned having to quickly finish the game so I admire the remaining effort that went into it.
Everyone walks pretty slow and if a boss is following you, it's pretty difficult to hit them without getting hit yourself. But hey, time constraints I'm guessing.
I actually beat the levels without using frost ray (forgot it exists), but what does E do? It spawns like a white guy with a blue axe.
Either way, given how little time you had, still a nice delivery so good job!