[Grind]

That would be really cool to have a crazy train wreck and defense mission to fend off whoever is attacking.

I really like games that add little stuff like that into their game, just to make it more fun. Maybe it doesn't have much to do with the main ideas of the game, but anything that keeps you on your guard, and kind of keeps the game out of the normal flow of things, helps a lot.

Maybe even have something like, if nobody has done some certain mission in a long time, like kill a bunch of mutants at some spot or something. Then the next time someone takes a train to that area it's all overrun and you have to fight off the train and stuff :D

I don't know, anything that keeps the game entertaining works for me