Use WASD to move your character. Touching the lava pool will make you return to the center. This project pretty much requires Turbo Mode to be playable.
This project isn't really a game or anything exciting. It's mostly just a demonstration of a technique. The way this project works is incredibly inefficient, and has no real applicable use. Now normally, with the 10 blocks challenge, you cannot use variables as anything but constants, because modifying variables requires a block you're not allowed to use. I got around this using the Goto block. You can Goto to a position with the precision of 0.00001th of a pixel. This has absolutely no effect to the player's eyes, so I can use that incredibly tiny sub-pixel number for Y velocity.