Use the left and right arrow keys to turn. Jump over the obstacles using the spacebar. Watch the size of the heart in the corner - it's your "health", or stamina. You lose it over time, and will have to collect the treats you find along the path to recover it! As you progress through the levels, your stamina will run out faster. The longer your horse can keep running, the closer you are to beating the High Score! Be careful about tripping over the obstacles, they will make you lose stamina too.
Thanks all who gave me feedback, ideas, and suggestions in previous versions! :) There's a new version! Questing: http://scratch.mit.edu/projects/11131449/ If the internet is busy, I recommend not playing in fullscreen. The bird call sounds are from SoundBible, but every other sound and image is made by me. Have fun!