For what little the game had, it was surprisingly enough for me to play the whole 30 minutes. Mainly I tried playing with the trees and conveyor belts (it didn't go so well fun wise ;D), but you do have a the start of something that could be developed into a full game. After reading the details, I understand that the time to make the game expired for your game about expiration ;P
I would certainly LOVE to see how you could build upon this. And for it being a 3D game is impressive since I mainly do 2D and have messed with pseudo 3D a bit. It was certainly a fun sandbox to play around in, great job!