Just finished the "EpicNameBro" challenge in Dark Souls last month (though I added a couple extra criteria of my own):
*You cannot level
*You can only use your starting equipment, rings are ok
*Can only upgrade through Andre (in other words, your starting weapon can only be normal, raw, divine, or occult)
*No healing, ever (the cleric's Heal miracle is the only exception)
*No covenants (cleric and knight just stay in Way of White)
*If starting as a pyromancer, you cannot upgrade your pyromancy flame
*No summons, ever
*No Head's-up Display
Did this with a wanderer. Getting used to not having a HUD was a chore.
Also, pick a Touhou game, any one will do. If that alone isn't hard enough for you, try to do a 1cc challenge on its hardest difficulty.
That jazz is insane, yo.