There were actually very few 3D assets in the projection device -- the Green building model /u/andaphantie mentions was originally created in magicavoxel but nearly all other art assets in the game were 2D images and drawings in isometric perspective that members of the art team created in a variety of different programs (including Photoshop, Clip Studio, Krita, and Inkscape).
Great. I don't know if you already stopped by/signed up, but come by 56-169. Sorry, I just saw this. Also, request access to our google group at https://groups.google.com/forum/#!forum/test-solution-please-ignore