RetroFE is a graphical launcher for various emulators. It is designed to be a free and open-source alternative to HyperSpin. While commonly referred to as a frontend to emulators, it is not designed for this purpose, instead to simply launch a particular game on a particular emulator. A frontend handles the audio and video of the backend.
RetroFE follows the same paradigm as HyperSpin. There aren't a lot of templates yet, but eventually someone will batch convert hyperspin themes.