Thanks for the feedback!
Indeed, it's optimized for that many, although I'd be able to see fewer. If you only have one Vizier, you do of course eliminate any threat of the Vizier being overthrown. Looking back, if I were to add any rule, it'd be that the Sunlord must select at least enough Viziers to overthrow them. If there were more words allowed, I'd have created an organic incentive (losing access to key government features, like, say, an army if no Viziers are appointed to that position). But alas, you are quite right, in the current iteration, it certainly needs a full-size traditional gaming group. That said, this would be madness with even just a few more than five players.
As with much in the world, it would indeed also be more fun intoxicated.
I greatly appreciate the prophet of the next generation of world entertainment leaving a comment on my humble RPG. Best of luck to you, my favorite internet alpaca.