I have played so, so many Sokoban-like block pushing games in my life, many of which have used almost this mechanic, so I'm gonna go way too deep in this comment. I'm just a really big fan of the genre and always enjoy seeing a new twist, and there's a few things here I haven't seen before.

I like that the motivation for moving in this way is because the block is not a block but a sheep. Often there's no reasoning at all why things should move this strange way, or as someone mentioned below, the block is just a block and the ground is ice. And for the jam theme, having it be the sheep who are forced to make a move, rather than the player, is a nice interpretation.

Having the prod be its own button, rather than coming from pushing in that direction, is also interesting. I noticed that if I line sheep up next to me on two sides, I can send two sheep in different directions at once. This mechanic isn't ever used in this set of puzzles, but I imagine a puzzle could be set up that makes use of it.

Having the grass be an area, rather than having specific exact spots the sheep must go, is also different from what I've seen in other games. It opens up the possibilities of what the end state could be, which can actually make the puzzles more difficult to solve, which is counterintuitive to the fact that there's in theory more places to win. But especially for this kind of puzzle, once your brain starts to get how to work backwards from the desired end state, the puzzles aren't so interesting anymore, and so having that be a wider open field keeps things fresh.

And finally, this isn't a pure grid based puzzle game the way many others are. Sheep can not quite line up with each other and still collide, and you can approach a sheep from slight variations of position (for example if you want to hit two sheep at once, or avoid hitting two sheep at once). In this game, in the first level with two sheep at first I thought perhaps it was a flaw, but then again, the level would have been less interesting if I could have been sure that they would collide before I tried it. 

I ended up enjoying that there was some exploration and slight unknowns, some "let me try this and see if it works", that there's a point to actually playing the level, rather than seeing the answer and having playing it out be a chore. Especially in the last level, where I actually had to try a couple different ideas to see what would collide where and what would land on the grass.

I can see that you've put thought into the level design and the order of levels, to reveal mechanics and teach the player what's possible bit by bit. That's another thing I love about this genre! I'm sure there's a ton of interesting puzzles just waiting to be designed for the particular variation of mechanics you have here, and perhaps more kinds of sheep with fun sheep behaviors.

And made so quickly! I'm impressed.

Fun recreation of that ice puzzle from old games!

It picked up in difficulty really nicely, loved the experience of playing it, nice job.

The last level gave me a hard time!

It was a kind of Sokoban for shepherds. A game made for me :D I really enjoyed it!