You're a wild west cowboy and you have to get all the gold you can. Ride your horse and shoot the bad guys trying to kill you. Use arrow keys or WASD to move and mouse to shoot.
You're in a weird red planet and there are many alien bugs trying to attack you. Shoot them and save your life. Use WASD to move, shoot with the mouse and R to recharge.
Shoot enemies at point-blank range and kill them. Use W, A, S, D or arrow keys to move and mouse to shoot. Keys 1,2,3,4,5,6 to change weapons and space bar to throw grenades.