The final upgrades need a MAJOR jump in coins required. I sleptwalked through the last 6 levels. Needs balance. Ended up not even using the last 5 weapons.
Fun game thou except for when everything becomes trivial. Also, what the hell with the bosses. The first boss was by far the hardest one in the game. 2nd boss, cake. 3 boss, pretty challenging. Final Boss was pathetically easy even after going back and debuffing myself.