Zombie Assault 2 in Adventure

Instructions 

Use the WASD or arrow keys to control your character; the Q and E keys will let you swap through available weapons. To throw a grenade, hit the G key, but keep in mind that they're hard to come by. As you kill more and more of the undead, you'll earn cash - use it to purchase new weapons and better barriers. Also, you'll gain experience with every skill, and your rank (and skills) will upgrade accordingly. Hit the spacebar to pause the game (and buy new weapons) as needed.