Arrow keys to move. Don't touch the lava (The brighter red). Immunity means you are immune to the lava for one turn. Hearts are purple, and if you run out of hearts, the game is over. Your goal is to get as many gems as possible. The chests contain 1-10 gems.
Thanks to @AwesomeFalconDragon When you are on level 1 to get to level 2, go to the edge of the screen and click the unicorn.