I'm not exactly sure what is off topic either!
I will say that not only cán US law (or any nation's legal system) be gamified, but the law is in fact already a game. The rules that govern it, the costumes, the setting it happens in -- all of these things demonstrate its essential, gamelike nature.
Check out Huizenga's Homo Ludens.
As for the question at hand:
Happily, I think much of the work has already been done for you! We already have the Core Rule Book, which would include the (US & State/Commwealth) Constitutions and the Rules particular to the actual Game itself and probably essentials like Blacks Law Dictionary.
The Player Handbook would include not only the Code of whatever state the DM has chosen to play in for this particular game, but also the rules governing specific situations (arbitration settings, courtroom protocols, etc).
Lastly the Expansion Packs already exist in works such as B., B., G. & H.'s Fundamentals of Property Law or E., K., W., B., C. & E.'s Family Law: Cases, Text, Problems or W. & F.'s Code of Canon Law Annotated.
For the question of gamifying, since it's (generally longaeval) Dragons and Gryphons, there's really no reason to reduce the material as they'd have plenty of time to learn. But if you still want reduction in amount of material, then there's no reason that the game publishers couldn't create editions that consist solely of digests or summations and statements.
As for the closure rationale & what you can do about it:
There's not really much you can do about it. You just have to wait and see if enough folks decide to reopen.
I think the question is straight up worldbuilding. It's no different than gamifying the activity we call War (also see Homo Ludens) and calling it RISK or even CHESS.