You start out super slow and sluggish, like you're attached to a pole like a rubber band. Your bullets do jack shit, only getting decent after the 3rd upgrade or so. Enemies start out faster than you so if you're running away from one and another appears behind you you're gonna die guaranteed. The upgrades themselves arbitrarily vary between cost, sometimes reasonable, other times way too high. The thing is if you get lucky enough and are given the right upgrades at the right price it starts being a little fun, and then the game suddenly stops and you realize you can only go up to wave 9.