Use the keyboard to control little Max, the hero, while with the mouse you control the magic marker, thanks to which you can draw anything you want to help Max in his adventure.
A good example of how you can use the marker is to create a staircase which Max can climb up to a higher zone. But there are tons of other possibilities: like drawing grills over jets of water that will then lift you to a platform, or creating balls to knock over objects.
The game has fifteen levels set in three different worlds. Each of those is full of puzzles, platforms, and enemies that you'll have to defeat with your own ingenuity - and a magic marker.
You'll only be able to play the first world in the demo version.