Make a military weapons and equipment from 1800 to the modern day mod, and make it so that there are many more floors in the cave, and allow enemies to also get weapons, enemies in deeper floors get better weapons and gear. Make it so that when someone, including the player, is downed, they get dragged to safety like how a medic would drag a wounded soldier. Also make a mod which adds machines which the children man in a mass production line indoors or in extremely upgradeable factories.