Woah. This trailer for Remnants of Earth is about as Second Life as you can get, but still -- it's an MMO inside of an MMO, and it looks bonkers.
Via New World Notes, Remnants of Earth is a cyberpunk game within Second Life. The developers explain:
[Remnants of Earth has a] heavy basis around classic pen and paper RPGs elements, like; dice rolling, stats, monster fighting, story driven events, MMO-like adventuring, and gathering. RoE is the first second life pen and paper table top game in SL, while still keeping the core features of any other roleplay sim. Players can interact with NPCs and other players to accomplish goals, and even engage in heated PvP faction wars. We even have a full crafting and mining system! Think of RoE as a fully functioning table top game in SL, like Dungeons and Dragons, or ShadowRun.
Some more screenshots: