While looking for encoder options I was surprised to find quite a few options ranging from some cheap Zero delay UBS encoders to the Ipac 2 and Ipac 4 as well as a hat that sits on a Pi 3b+.
I also found some made from old USB Keyboards. I am not sure if using one board per player is the way to go with these. Which is what you would do with the Zero delay USB encoders.
I had a spare old USB encoder and so rather then buy parts I have decided to use that. I kind of like the idea of putting a old keyboard top use idea.
Having removed the PCB from the old keyboard, I then sanded away the black conductive coating on the pads and then tinned them with solder.
Next I tinned the ribbon cables and soldered them on place. I could have just identified the connections I need and only soldered wires for them. However, I am going to take all of them to a strip board and then put a terminal or a socket on for each wire.