For level 19, you have to make a tower of yourself with you on the bottom and at least 6 shadows, then walk over the bridge and the top shadow should reach the goal.
It was pretty fun. Too easy though, and after a while, it becomes a game where you just hold down the left click button. My strategy was to buy elevators whenever available, and buy 1 power blast and 2 laser cannons. Enemies didn't come half way to my elevators.
 "Dodge"){kind=icon}
 "Platform Racing"){kind=icon}
 "Electric Box"){kind=icon}
 "The Company of Myself"){kind=icon}
 "The Next Floor"){kind=icon}