>>20A chess variant is easier to design
yeah, so what? it has little appeal to people who want to design video games as there's not much self-expression there (at least when compared to normal game design), it has even less appeal to gamers as it's just endless variations on the same centuries-old game and it doesn't even have much appeal for chess players as they usually try to get better at traditional chess. it's something you'd like because you like chess variants but you must admit it's a niche interest - even when compared to pre-existing Linux gaming (e.g. NetHack - this is far from mainstream but it has a more understandable appeal than 'chess but you must check dubs').
You could sculpt a 3D object by hand, paint it and pop-in a virtual keyboard, add a simple script and the object will start running it instantly. Now imagine this done in Blender/Unity/whatever. Its like writing code in Common Lisp inside a live system (Read-Eval-Print).
the key element in your description is the usage of motion control for the creation of 3D graphics combined with a VR-based live coding environment. this sounds less like SL and more like an extremely modernized Smalltalk environment.