Permanent URL: https://mezzacotta.net/postcard/?comic=4979
Denying any responsibility for this is: David Morgan-Mar
The author writes:
Many people have tried to invent and popularise various versions of three-dimensional chess, and there have even been attempts at making playable four-dimensional and five-dimensional chess. But Preston's infinite-dimensional chess, played in a Hilbert space, as seen in today's comic, is a real game that I've worked out. The rules are available here.
As you can see from a read through of the rules, it's eminently playable, as long as you have time to take an infinite number of turns.