StepMania theme structure

StepMania themes consist of various files and directories.

Overview
Most folders are shared by all "modern" (3.9 and up) StepMania versions.

StepMania\ |_ default\ |_ BGAnimations\ |_ Fonts\ |_ Graphics\ |_ Sounds\ |_ Metrics.ini |_ ThemeInfo.ini
 * _ Themes\

StepMania 3.9 contains a separate  directory, while StepMania 3.95 and 4.0 ditch the Numbers directory and added   instead.

Metrics.ini
The metrics are the core of a StepMania theme (though they are less important in StepMania 4, depending on your theming style).

ThemeInfo.ini
ThemeInfo is a StepMania 4-only file used to display the theme's name in the options. In sm-ssc, you can also put the theme's author in this file.