SuperTux
Classic 2D jump'n'run sidescroller with Tux the penguin. You run and jump through several worlds and fight your enemies by jumping on them, bumping into them from below or throwing objects at them and collecting power-ups and other items along the way.
Story
Tux and Penny were having a nice picnic on the ice fields of Antarctica. Suddenly, a creature jumped out from behind an ice bush, there was a flash and Tux fell asleep! When Tux wakes up, he realizes that Penny has disappeared. There is now a letter where she used to lie: "Tux, my arch-enemy! I have captured your beautiful Penny and brought her to my fortress. The road to my fortress is littered with my henchmen. Give up the idea of trying to get her back, you don't stand a chance!" - Nolok Tux looks up and sees Nolok's fortress in the distance. Determined to save his beloved Penny, he begins his journey.