Someone mentioned the possibility of a crouch function, and I'd like to echo that. I just stopped playing at 3-2 because the tiki statues were too annoying to deal with. Jumping the fireballs and the spikes at the same time proved futile, especially with the overlapping ranges. The range of the tiki statues was way too high; I kept getting hit almost two screens away from the statue, especially on the stairs with minions marching down.
And, as always, fix the kupon issue. I didn't buy anything but the first sword, and I still had to grind for the second sword. If the player needs a main item before I can possibly afford it, something is off.