The videos on the game (and all his other videos) with Irving Finkel, a curator at the British museum, are spellbinding. He has the looks, manners and enthusiasm of an eccentric museum curator from central casting!
This is much more palatable and cool since they’re not just randomly guessing what the game can be like this article is
They are creating a probability distribution function where each point is a different gameplay ruleset and then we are free to pick the gameplay ruleset with the highest probability, with the caveat that there are other similar gameplays, with slightly different rules, and almost the same probability. And there are other gameplay rules with much lower probability because they don't match the wear of the board.
A random guess would have a flat distribution where any gameplay has the same probability.