StepMania is a cross-platform rhythm video game and engine. It was originally developed as a simulator of Konamis arcade game series Dance Dance Revolution, and has since evolved into an extensible rhythm game engine capable of supporting a variety of rhythm-based game types.
License: Open Source
Osu! and StepMania are both rhythm games with strong community support, but they cater to different audiences. Osu! offers a more casual experience with a variety of game modes and user-generated content, while StepMania focuses on technical skill and customization.