What is this unused rainbow octopus cable for?

I finished assembling mine and it boots up and works correctly, both with the normal case and with the litekey accessory, but I am left over with an extra cable that I dont know what to do with. This cable isn’t on the parts list or in the instructions. It has a large connector on one end that branches out to 14 individual connectors with different colored wires. What is this used for?

That’s the “debug” cable. It connect to the bottom connector on the ClockworkPi and give access so some IO like the physical RS232 serial port.

Unless you really want to tinker with the hardware you can keep it in the box as you would not need it to build the GameShell.