the following text goes to any skilled programmer looking for ideas
We need meele weapons! That should be really amazing, dont'cha think? Ran outta ammo? bonk theyr heads out! huzzah!
What about adding extra classes that actually are related to the game? I'm a cave story fan but...geez
Archievements! Everyone loves those, and they could actually fit with the "other extra characters" idea, since it's pretty easy to find about how to "unlock" those two...
Well, that's all I have for now, just ideas