All levels unlocked.
Flakboy's back for another beating, so bust out the arsenal and show him what you've got!
Scroll over the categories, clicking the weapons you want to add and dragging them into place (border must be green). Place the rubber ducky in the room to finish your destructive deathtrap's design, then hit "Go" to see how Flakboy holds up. You need to reach the damage target in order to proceed to the next level.