Well only considering recent games I would go with Halo 3 single player on legendary with all skulls on, I believe only 2 people have ever beat it on those settings. Also the downloadable Master Ninja tournament pack for Ninja Gaiden, I couldn't even get past the second boss and I'm pretty good at the game.
Considering oldschool games I would go with Super Godzilla for the snes. That bullshit game had no saves and the cheapest bosses I have ever fought. lol it almost sickens me thinking of that game.
The definitive evidence that video games turn people into mass murderers








