1. Frustration Levels - Super Mario Bros.
While not technically real levels, these are among some of the most interestingly designed levels in any game. They can be played via ROM and emulator, or in various online versions. While not impossible, they are ridiculously hard, with unstable physics pulling out a number of unpleasant surprises on the player. Even the most experienced Mario players will undoubtedly shout "WTF?!?" in frustration while playing these levels, which are best played only if you a) have a very mild temperament and b) are bloody good at Mario! If you need any further indication that these levels live up to their name, you need only check out the litany of profanity-laden videos floating around online, as so-called Mario "experts" try their damnest (in vain) to make their way through these levels. Hilarious. If you want more "WTF?!? Video Game Levels" or have your own, leave a comment!