This game got too easy after Flamethrower was unlocked, but other than that, I loved the difficulty and challenge on level 4. Level 3 isn't as bad as people say if you just use the Shotgun. And at first I was trying to shoot where the gun was aiming.. and later noticed there were crosshairs. Other than that, great game! And I'll give it a 5/5, it was fun enough to make me go for 140 antidotes.