Wow, this is very impressive. Some people say that anything that can be done in a C-type language will be done in JS between five and ten years later -- this is evidence for that point.
The gameplay feels nice, and it reminds me of Caesar II, if that game is familiar to anyone. That being said, I think the game would benefit from introducing a few objectives.
About Caesar II/III, it was a nice city building game. But the 3DCity game is very similar to another game called SimCity/SimCity2000. Some mentioned in this thread that it even uses the open source code of the original SimCity 1 for its city simulation code.
The gameplay feels nice, and it reminds me of Caesar II, if that game is familiar to anyone. That being said, I think the game would benefit from introducing a few objectives.