an "A" for effort
the enemies all walk directly towards you, only leaving room for differences in size, speed, how much money they drop, and endurance(health bar).
the weapons were all the same. you click on a enemy and they take damage. the only real difference was that if i leveled up one weapon, all the others were weaker(and even then, not by much).
i didn't notice any increase of money as i got further into the game. maybe it's just me but i believe that the further you go into a game the more money you deserve per level.
I also felt that as bought weapons they seemed to show up less. maybe it's a coincidence, but in that case, why do the weapon drops chance randomly and unpredictably change in each level.
if any of this is wrong, it's because i couldn't focus on the game for long enough to get far enough in to find anything interesting. at first i thought it was just taking a while to get to the good stuff, but it was taking to long, so i gave up.
on the other hand you seem to have put a lot of effort into this. i hate to slag other peoples work when you put so much into it, but this is what the reviews are for.