Why not toss some schools in there while we're at it so everyone can learn about why that may not work well..

That mission would definitely get the game banned in ~40 countries.

I suggest not adding buildings at all. For obvious reasons. Also it is quite obvious that it would be a bad idea to add cars in the game. Obviously there shouldn't be humans. Animals? Well, obviously it would be bad. Roads are ok, I suppose, but obviously it would be better to avoid them. Same with trees.

There should be a mission at the Kaaba.