Xuri, from your Discord post:
Another approach could be to store a list of character serials for each house, maybe in a flat txt file in the shared folder. Doesn't affect world save times or world load times, and if no one visits the house, no overhead. Each time a character visits a public house, their serial gets stored along with timestamp in a flat file unique to that particular house. Every now and then, I could have the house prune the list of visitors (delete any entries older than 24 hours). Perhaps every time someone visits the house and more than X amount of time has passed since last pruning occurred.
Another thing you could do with a system like this is give npcs some memory of talking to PCs. When a player talks to npc, the pc serial and npc serial is stored with the timestamp, etc. Maybe the npc has different onspeech options that are available from frequent visits, etc. Maybe it tracks donated gold to beggar and the beggar gives quest clues or something to those who periodically donate, etc. and then Skynet.
