A RPG with a self-sustaining economic engine that causes the NPC fighters to go out and start fights with each other without the player needing to be involved.
What attributes would be needed for an auto-Touhou game? What components are needed for an engine for NPCs to automatically start fights with each other and go home while the uninvolved player wanders around doing the player quests.
A table/graph of everybody's relationships towards each other:
Mechanisms for triggering a desire to fight.
The game needs a something-to-do engine. Different characters will have different character-appropriate choices of something to do. The engine will select something to do from a task list. Each task may have:
A mechanism of classifying tasks so that “beat up specific person” will also fulfill the task of “beat up somebody”.
The game needs an Incident recognition engine. When NPCs (or the player) do something that qualifies as an Incident, other NPCs need to recognize it.
NPCs must recognize when a person enters the area and choose how to react: ignore, greet, insult, start fight. The AI should store the time the person was met so this process does not repeat itself if the person leaves and immediately returns.
A communication engine for sending simple messages:
Sinks and supplies and costs and benefits