I wanna be the guy
(note: the official full title is "I wanna be the guy: The Movie: The Game")
From Finale's description: "I Wanna Be The Guy: The Movie: The Game is a sardonic loveletter to the halcyon days of early American videogaming, packaged as a nail-rippingly difficult platform adventure. Players fill the role of The Kid, a youthful, vaguely Megaman-esque protagonist on a quest to become The Guy. This inscrutable plot, however, is just a vehicle for a wide variety of inventive, well-designed and frustrating jump-and-shoot challenges that pay homage to many of the games you loved as a child. The ever-fragile Kid explodes in a shower of red pixels at the slightest brush from the game's many obstacles, from traditional spikes and bottomless pits to more unconventional killers, such as plantlife and puzzle pieces."
There are four difficulty settings in the game: Normal, Hard, Very Hard, and Impossible. The main difference between the difficulties it the quantity of save points.
Adam Nelson is working on a walkthrough for the game. You can check out the latest version in this forum topic.
Neodraken has a full map of the game in this forum topic.
A list of the numerous video walkthroughs is maintained in this forum topic by catldr24.
UltraJMan has a let's play for this game in 50+ parts, the first part of which follows here:
There's a rather impressive (though incomplete) run of the left side of the game on impossible mode by KyperTrast here:
Completed in a 3-part video by tijitdamijit:
Bowser and Friends