agree with a lot of the previous comments. badges, more upgrades. like how long needing to hold mouse would be "full power". shotgun is extremely overpowered and on any difficulty honestly the only gun worth upgrading. upgrade wall, mines, and shotgun and you'll beat any level easily. if you only upgrade shotgun they only drop shotgun ammo, making it that much easier. game is also not difficult enough - you can beat easy if you are nearly black out drunk, and hard is a easy to medium at best.
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