I thought it could be a fun idea to have a thread where we share some ideas that never found their way into games, never got passed the initial "this could be fun" stage, or you just haven't had time to work on. Maybe they'll inspire someone else use them, or you'll find that someone already made a game like it.
I'll start:
A game where you play a civilization that discovers am unmanned exploratory satellite and have to make sense of culture that sent it based on what they included in it.