New Weapons
You can target enemies with the mouse pointer and shoot them by clicking. Cody can pick up many different weapons during the game, but he can only carry two at a time. When you try to pick up a third weapon, the one you have equipped at that time will be dropped. Toggle between guns by pressing E or 1 before you pick up a new gun to drop your other weapon instead. When you pick up a gun, it will not be fully charged. To load up your gun with a full charge, pick up a second copy of the same gun. Picking up a third copy won't do anything, however.
Losing Weapons
Every time you get hurt by a teddy bear zombie or another monster, your health bar will decrease. If it runs out altogether, you will automatically drop your currently equipped weapon. If you don't want to lose your primary weapon, hit E or 1 to drop your secondary weapon instead. You only have a very brief half-second window to do this, so be ready.
Moving and Jumping
Move Cody left and right using the left and right arrow keys or the A and D keys. S or the down arrow will make him duck -- hit S or down twice to make Cody drop through a platform. The up arrow or W makes him jump up. You can jump higher by shooting your guns at the ground at the beginning of your jump. To execute wall jumps, jump while running toward a wall; as Cody begins to slide down the wall, jump and press the opposite directional key at the same time. If you have two walls close together, it's possible to jump all the way to the top by alternating between them.
Score Multipliers
When you begin playing, you'll be offered the option to change your level. Deputy and Sheriff are harder than the first level -- Civilian -- but Deputy offers double your basic score, and Sheriff will triple it. You can also multiply your score by avoiding hits from zombie bears or other enemies.
Pausing the Action
If you need to take a break, hit P to pause the game. The game will also pause automatically if you move your mouse pointer outside the game screen.