bospor

Some sort of weather or disaster that would force ppl indoors would add some randomness to the game. Kind of like a Blowout in Stalker. You don't get inside on time, become a zombie! :)

Arma engine is really not that good. Building underground would require building one layer of island on the top of another. So much work! I doubt we would ever see it. Martin tried that on Taviana, but only has a few tunnels and they are just straight corridors. I bet that's a lot of work for him to create the entire network of tunnels under the city. That's another year of modding. Even though Metro 2033 in Arma would be awesome!