Do you guys know about Liar Game?
It's a great manga by Kaitani Shinobu (info here).
It's a manga with 'mind-battle' as it's theme. Where you must lie, and trick your opponent, and you'll get enourmous amount of money if you win. BUT IF YOU LOSE, you'll be in enormous debt instead.
I'm pretty sure some of you are wondering : SO WHAT THE HELL DO YOU MEAN BY TOUHOU?!
Ponjiyuusu, another manga/doujin author, made this great doujin called Touhou : Gensokyo's Liar Game (info here).
You'll be able to see the Liar Game, Touhou-styled. With the mind-battle stuffs, and of course, with Touhou's awesome magic performances.
Thanks to Gaku Gaku Animal Land for scanlating this awesome doujin. You may find the first chapter in here