Press space bar or up arrow to jump. Press both to jump double the height. If you hold down the space bar and up arrow key, you will levitate in the air. If you touch the gray obsticle, you will lose.
Here is a demo of a game that I will be working on. Basically you are a square that moves. The only thing that you can control is the squares jump. My plan for this game is to make 15 levels, but since I am working on other scratch projects, it will take me a while to complete. This is the full version: http://scratch.mit.edu/projects/Supercool789/2458173