Appears that the final building is incorrectly priced. It colors in at the listed price, but instead of 7500 it appears to be more like 10000 to actually be able to buy and place it.

Another fun thing: If you leave as much space untouched as possible, the code doesn't actually clear out nature when the planet does a kaboom (only building stuff the player placed), so you can have your dead planet have a nice tree beard XD

A bit too simple for my tastes, but it wasssssssss made in 48 hours, so not bad.