Thing Thing 4
Kill 100,000 enemies with any weapon, complete the armory, and successfully complete the game under the Hard difficulty setting.
Kill 500 enemies with the lead pipe.
Faster firing gun
Note: This only works with automatic guns (SMGs and assault rifles). To fire your gun faster, repeatedly click the Left Mouse Button. Your gun will fire faster, but it will also recoil harder. When this happens, just move your Mouse down.