If you get a battery from Adafruit, you will need to replace the connector with one of these.
https://www.amazon.com/gp/product/B0738CV1LP/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
BE AWARE: The wires in the link above have the polarity reversed. You will need to solder red to black and black to red for your battery to work. Consult your included battery, pcb, and wire before you do bad things to your GameShell!
But, it does work!