It would be interesting to introduce some hazards in mining, such as water sources, lava pools, underground monster dwellings, etc. This would be extra challenging if resources weren't all mapped at the start of the game.
I've been planning this for some time, but didn't get around to it. I've added water in Alpha7 though. Putting the dwarves and other settlements on the same level in the mountain would be best probably.
Cave-ins would also probably be an interesting hazard. When digging there would be a (low but present) chance of triggering a cave-in which would kill the digging Imp along with any nearby minions. If wall building is implemented, then dirt walls would also have a tiny chance of caving in every turn. Stone/reinforced walls wouldn't be subject to cave-ins.
