As a way to reset recoil and ammo for a gun (Not those with one in the clip) you can press "z" then "x" really fast to switch guns and back the one you were using. Switching guns resets the ammo count for that gun and the recoil. Better than waiting for the reload to finish. For maximum efficiency, switch when there's 1 or 2 ammo left.
I reckon there should also be a 'custom game' option after you finish the last boss where you pick a map, number of opposing teams, and how many people per team, what armour they have and the AI difficulty. That in addition to badges and multiplayer.
I love the game. Simply great. A good end-level interface as well, which a replay, next level, level select and upgrades. It would be awesome if there was a 'stats' page, with enemies killed, types of enemies killed, shots fired from each weapon, how many 'superpowers' from each weapon used, favourite weapon, etc.