it should be harder
i beat the game the second time I played, meaning I beat the game in less than half an hour.
It was way too easy. My strategy was to max out my health recovery and machine gun. Thats pretty much the only weapon I used, I didn't find a use for the grenades.
Upgrades should cost more. Maybe the use of specific weapons on specific enemies? That might make it harder since I would have been forced to switch weapons.
All in all, it was fun.