Move the bat left and right using the arrow keys. Don't run into trees, and try to survive for as long as possible. At twenty seconds, a tree will pop up in the center. see how long you can survive past then! If you would like to "turn off" the center tree, press 'e'.
This was one of the first projects I started on, but I soon came to a point where I couldn't figure out how to do it. I pretty much restarted when I came across it again and made it actually function. Thanks to my design teacher for introducing me to scratch!