I started a challenge game on medium difficulty. I went to place a shop down and then tried to custom build a building around it. However, I have nothing to choose from; there is no walls, roofs, nothing. All state nothing researched. Ok, no problem so I go into research and research everything but rollercoasters and rides. The strange thing is through this I never get any themes or building options to research and stuck within no ability to custom build anything. I am pretty sure I am missing something and I hope this community is able to help me figure out what I am stupidly missing.