Converting Four Panels to a digital form would presumably be quite challenging.

Not exactly challenging, but annoying and frustrating. I had a basic prototype of a client-side MSPaint-style drawing interface, but when it came to figuring out the multiplayer parts it's hard to play around with prototypes cheaply. On one hand my inclination would be to think you could do it directly through the chain since it's essentially a big database for coordinating transaction information, but getting info out of the chain always seems to be a bigger headache than I expect. So that suggests figuring out the basic functionality and then integrating the chain later. But the alternatives aren't easy to work with either, the free services like Heroku all tend to have weird restrictions, like never storing anything to a disk, so you have to architect around them, but carefully architecting a solution is not a good fit for a quick-and-dirty prototype. So, since I don't want to invest any resources up front, I get stuck trying to find the least bad options, and that is motivation-draining.