Play the original Super Mario Bros. on an emulator with the frameskip cranked up so it run on super high speed. Took us a few attempts to get the timing right just to not die to the first goomba who strolls at you at (in normal speed) a leisurely pace.

I'm a big fan of the early Mega Man X games, so I often do stuff like 'beat the game w/o special weapons', 'beat the game w/o dashing' ect...

In FFT I've played so many times that every new playthrough I try and set up some rules I have to work my party within.

I only ever do stuff like this to games that I love and have beaten several times already, on a new game I always work with all the stuff I have available. (Unless I consider it stupid enough it ruins the game experience)