I have a better idea. Every user must have a holozing tattoo on their right arm to play the game. Each tattoo is unique because it has a certain invisible dot matrix. This way it can be guaranteed that only this body with the respective username can play the game. In this way you can combine ZKP with a continuous check of the user as you can check the tattoo every few hours or days using a webcam.
This was just a joke ;)