.SMZIP File Extension
What is an SMZIP file?
Package format used by StepMania, a free dance and rhythm game that supports dance pads; typically created with the StepMania Package Exporter (smpackage.exe); includes the music, announcers, themes, and other add-ons for a specific song; designed to be a simple format for distributing song data in a single file.
StepMania packages can be installed by simply double-clicking the SMZIP file if StepMania is installed on the system. This extracts all the files in the package to the main StepMania program folder.
Since the SMZIP file uses .ZIP compression, you can also rename the file extension to ".zip" and extract the contents with a file decompression program.