Use the up arrow to jump. Jump over the logs to get points, or lose a life by hitting them. Get extra lives by jumping to hit the life tokens overhead. After twenty seconds, a second set of logs appear. After another twenty, another set. (This doesn't happen every twenty seconds, or the game would just have infinite logs.)
This was originally going to be Pitfall, but this turned out slightly different. I may improve it later, so check back to see if it's changed! The next big edit would be to add sounds, so stay tuned to see when it's added.