Needful things (simple additions to improve the game)

So I’m very interested in this npc’s appearing in houses thing…I’m looking into some kind of lua based setup and so far I’ve determined it’s possible to place and npc, but I’m still trying to figure out the triggering events. Ideally I’d like it to fire when a specific overmap tile is generated, with a percentage chance of placing an npc. class_defenitions.lua is intimidating lol…