We're glad you liked the concept! Thanks for all the suggestions!
Exiting after a game makes so much sense, we'll add it after the jam!
Our thinking for having sand and soil is that sand is for when you need a little bit of a finer filler material, where as dirt is larger. It also adds diversity so you can do some funky layering and mix it up! You can for sure complete all the levels by using one or the other, but we believe having a choice is good!
We thought it would be fun to grab them one by one from the box as a little surprise for what comes next, although we understand for retrying the level multiple times it could get tedious.