Oh God I can't believe you could muster the strength to finish that train wreck
Whoa. When I read the title, the first game that popped to mind was I Wanna Be The Guy, but thinking about it more... The Witness is definitely a contender for me, too. That game is challenging in a whole different way than most "traditionally hard" games. Excellent choice.Probably The Witness. The final challenge took me like eight hours of constant playing to finally do and it's not like you can use a guide either.