PuzzGun is a 2D retro styled puzzle solving platformer game by Aleski Rajamaki and Matias Rajamaki with easy-to-pick-up gameplay. The controls are easy to learn, and on level one you are shown a detailed illustration of each function. You play as a cowboy who decides he wants to explore a mysterious castle owned by an evil wizard. Apparently, nobody that entered the castle was ever seen again, and he wants to be an exception, of course. The wizard sees you right away, however, and enslaves you to the castle forever. Once you complete the 63 levels in the game (21 levels per section, no skipping levels), you will be freed from the castle.
Source: N4G PC PuzzGun review – ChristCenteredGamer