What are some alternatives?
When comparing RetroX and Happy Chick, you can also consider the following products
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
MESS - Emulates most gaming systems that exist, emphasizing accuracy over speed.
Mame - MAME stands for Multiple Arcade Machine Emulator.
higan - higan was formerly known as bsnes. The project was renamed after becoming a multi-system emulator.
Mednafen - Mednafen is a portable, utilizing OpenGL and SDL, argument(command-line)-driven multi-system...
OpenEmu - Console and Arcade video game emulator for macOS.