"I Wanna Be the Guy" is the hardest videogame ever created. It is a non linear maze which can lead the player purposfully in the wrong direction for hour upon frustrating hour. It has elements of a dupe.
This is the best run I have ever seen, but the player still doesn't get very far. Download it and give it a try if you'd like. You already know how to beat the first level. I DARE you.