SuperTux

SuperTux is a free and open-source two-dimensional platform game in the style of Nintendo's Super Mario Bros. The game features Tux, the Linux mascot, on a quest to rescue his kidnapped girlfriend, Penny, from the antagonist, Nolok.

SuperTux is written primarily in C++ and uses the SDL library. The game includes a variety of levels, enemies, and power-ups, and also features a level editor that allows players to create and share their own custom levels.

The game is licensed under the GNU General Public License and is available for a variety of operating systems, including Linux, macOS, Windows, and other Unix-like systems. It is developed by a community of volunteers and has been actively maintained and updated since its initial release. The gameplay is focused on jumping and running through levels, collecting power-ups such as eggs that give Tux abilities like shooting snowballs, and defeating enemies by jumping on them or shooting them. Progress is made by completing levels and navigating various worlds within the game.