It's a DIY, QMK Powered Trackball...for thumb ballers!
Make example for this keyboard (after setting up your build environment):
make ploopyco/trackball_thumb/rev1_001:default:flash
To jump to the bootloader, hold down "Button 4" (button closest to the USB port).
See the build environment setup and the make instructions for more information. Brand new to QMK? Start with our Complete Newbs Guide.
You can find customziation options here.