Mercs


 TIPS:

 On level 5 go to the very right of the screen - just before you reach
 the tank. There you will find a hedge blocking your way, so blast it
 until it explodes. Now you will be able to enter a secret area packed
 with pick-ups, including a clown's head. Pick up the head to be blessed
 with a mega-powerful weapon which kills everything on contact.