In Hitsuji Ya-i, you have to herd your sheep into the gate and close it. Starts out nice and easy, a single sheep and a curious passer-by type wolf. As was the style at the time, the game got harder as you progressed. The sheep became more numerous and the wolves got more aggressive by intentionally opening the gate after you've closed it, and also eventually start to grow their pack.

Hitsuji Ya-i seems more a Little Bo Peep game than Mary Had a Little Lamb, if you ask me, but the game is backed by the latter's music. Well, I suppose in their defense, Little Bo Peep doesn't have an actual song, at least that I've heard.