I'd like to contribute with the ideas already pinned here with more depth on the concept of each power up.
- Power ups that i think should be upgraded on stack, but NOT reset the timer: grabber speed, more ships and 2x score
- Power ups that should ONLY reset the timer: you shoot for free, piercing bullets
- Power ups that shouldn't exist: raining gold. The gold maker already have this function and raining gold only gets in the grabber's way for more power ups. It would improve the slaughter by avoiding power ups such as the waves of ships to get lost due of the amount of gold to be picked up before the power up itself is on grabber's range priority.
Plus, i don't think that chosing which power up should be picked contributes with the fun. The lucky factor is one of the funiest things here, so please leave it that way. The grabbers are drones, so that they grab whats nearby first. It's cool they have a personality.
 "10 More Bullets"){kind=icon}