SuperTux
A classic open-source side-scrolling platformer starring Tux the penguin, inspired by the original Super Mario games.
SuperTux is a classic 2D side-scrolling platformer game starring Tux the penguin, inspired by the early Super Mario games. Players jump across levels, stomp enemies, and overcome hazards to rescue Tux's friends.
The game features two distinct worlds to explore: an overworld with themed levels, secret bonus levels, and bosses. Powerups let Tux grow, use a stomping ability, or transform into different forms. The engine has been rewritten over time to improve performance and add effects.
SuperTux is licensed under GPL-3.0 and is completely free. It is built for desktop platforms including Linux, macOS, and Windows, and has an active community that creates additional levels. It does not require any paid game files.