I downloaded a city map and would love to play my own (or even smp) zombie survival game with looting/scavenging
Run a command, then the mod would detect doors and place a chest somewhere near the door. It would need to detect that a block doesn't exist so that it doesn't merge or replace the walls. Then, given a table of items that the player/owner would create so that it can include modded items, such as guns, it would spawn some random items from that loot table in the chests. Once the chest is looted, a timer would start and replace the chest with another set of random items. The rarity of which items could possibly spawn could be set by the player.