This is a great game. I didn't finish it, but I've got this bookmarked to play and finish later. Great concept (although probably not original), and level design complements the concept quite well.
Few comments.
1. Since one of the sheep is invincible, perhaps it should have been visually distinct to make it clear. Perhaps a more mechanized version of the sheep to emphasize its invincibility.
2. This game plays good enough that I would have liked more polish, things like death animation, better SFX (a sheep game without "baaa"?).
3. A screen size which allows me to see more of the level would improve the gameplay, since then I can plan my moves, etc.
Hope you build on it after the jam. :)