As a whim, I want to do something brutal, preferably with a low chance of success.
I was thinking of playing a One City Challenge, All War, Raging Barbarians, with a couple variant rules: Player must win via the Space Race, and the Player may not launch offensive strikes against the A.I. (that is, we couldn't make the late game easier by wiping out a few A.I. early). Not sure about difficulty since I'm not that familiar with All War. I figure at least Prince, but maybe higher.
If anyone's interested, or has ideas for making this more devious, contact me and I'll set up a thread.