So my idea (albeit a poor one) is a civilization-style web-based massively multiplayer video game. Map is randomly generated and number of players per map is limited. There are no pre-existing technologies or units, technologies and units are created by players and must be approved by other players (possibly players from other maps) before entering the game. The idea is the game could be open ended and vastly repeatable. The open ended nature of the game would allow for a lot of exploitation, so conquest would be minimized as a practical course of action. I imagine the focus being on economics and diplomacy.
That's pretty vague and not well thought out, but for some reason I found myself pondering it recently. Since the involvement by the developer could be minimized, by placing game management on players, the game could be free and monetized by ad revenue.