, the most stable way to find "complete" themes today is through specialized archives. Top Themes for StepMania 5.1 Lambda (The "Complete Paper" Default)
Some forks like Project OutFox (SM5.3) have preliminary support for 5.1 themes, but always check a theme's documentation to confirm compatibility before downloading. stepmania 5.1 themes
When downloading and testing new themes, keep an eye out for these essential quality-of-life features: Customizable Judgment Fonts , the most stable way to find "complete"