Thank you for the feedback. I am happy with how the core sand mechanic turned out, and indeed with our opening art. As for the cons:

-This may not be lag. There is a relatively low ground friction, as the sandman is floating. It can be compensated for, but it might be a bit overboard. I'm working on a version with at least a few fixes, I can try out some higher friction settings. 

-We were going for a bleak look in the level (at one point there were more levels planned, this was the loneliness level), but it is true that the result is pretty pale. We'd have liked to have it shift to a more colorful dream version as you completed the level, but that got scrapped for time.

-We had rathered a few sfx, but again ran out of time implementing them.

-We also wanted some sand-cloud particle effects or a trail of sandgrains, but again, we ran out of time.

I was planning to upload a slightly tweaked version (in addition to the current version, not replacing it), and I thought about adding sand particles too, but that felt less like a bugfix and more like adding new features. It didn't seem in spirit with the game jam's time limits to start adding features to the playable version. Or is that fine, as long as it's clearly marked as an updated version, and the original jam version is still available?