Clean-looking work.
Unfortunately, games which require you to mindlessly beat on your controller or keyboard weren't any fun for the Atari 2600, and they aren't any fun now.
Maybe you could have the zebras running across grassland, and rather than hammering away to determine their speed, you could control their stripes somewhat. There is a lion chasing both zebras, and the zebra which is slower to blend in will get caught and eaten.
An odd suggestion, sure, but I don't like to criticise nice work without offering some alternative.