What are they?

A launcher for the Odroid Go is a piece of software, or firmware that has the capability to act as a 'springboard' to launch additional applications directly from memory.

There are multiple Launchers available for the Odroid Go for launching emulators an emulator is hardware or software that enables one computer system (called the host) to behave like another computer system (called the guest). In this case, video game systems that can run ROMs (A ROM is a computer file which contains a copy of the data from a read-only memory chip, often from a video game cartridge)

Currently, the Odroid Go is distributed with the Go Play Launcher.

Another alternative Launcher firmware is the community built Retro ESP32