Vivid Unit comes with decent CPU and RAM, 1280x720 screen and a speaker on board, all these make it a perfect hardware for running retro games. You may want to connect a joystick or a real keyboard to the USB port for better experience though.
In order to run retro games on Vivid Unit, you need to install emulator(s) for the system(s). We recommend RetroPie, which will install the most popular emulators to your device and provide a unified managing interface.
