The dangers aren't always apparent so be careful. Your first stickman won't survive nor your second and probably more won't survive. So try and get through all 20 levels using as few stickmen as possible. Use the WAD or arrow keys on the keyboard to move. On touch devices use the on-screen arrows. Progress is automatically saved at the end of each level. After clicking the Play button you will be given the option to continue the previous game or reset your progress. This assumes you have completed a level previously and not deleted your browser's cache.