I played through the whole game for that shitty ending?!
This game is not good at all. It's an extremely boring grindfest where all you do is collect money to survive the attacks from the enemies in the later levels who will one-shot you if you don't have the right armor. There are no bosses, the game is very slow-paced and the enemies are hard to hit. And there is no point in using anything other than the bounce mod as it has the fastest rate of fire. The "advantages and disadvantages" from the other mods are completely negligible since all the bullets do the exact same amount of damage, meaning that the only thing that's really different about them is the rate of fire.
I spent an hour playing this game to see a terrible two-screen ending that took me right back to the title screen afterwards. Don't waste your time on this game, folks. The only thing that's even remotely interesting from this snorefest is the music, and it's really not that great. Definitely NOT worth playing through the game to hear. Just give this one a pass, you'll thank me later.