Large map. Godlike AI. 6 opponents. No tech trading/brokering. All victory conditions enabled. No weird settings (although making ascenion crystals "rare" helps a lot, but is kind of cheesy). The only planets you can get besides Earth and Mars are either through galactic events or things like Brindle's.
I've only been able to do it twice, and everything broke my way both times. The strategy is pretty simple: survive, turtle, go for the research win, and try to keep any one AI from getting to powerful.