110% this. Mage Knight is the classic example of how to do this wrong. I love the game, but seriously, there are rules in the ‘Learn to Play’ book that are never mentioned in the ‘Rules Refernce’ book (or whatever the books are called). At least, that’s with the 1st printing that I’ve had since it came out. Hopefully that’s gotten better.
On the other end of the spectrum, I got Mansions of Madness 2e to the table last night, and the split rulebooks for that are divine- the Rules Reference is really just an extended and detailed glossary of every term and system in the game, all in alpha order, and cross-referenced. It makes looking up anything at all a snap.
I played it a few years back, and own 1e and a bunch of expansions, but was always put off a little by the price, and fairly limited number of scenarios (5 in the base game, plus 2 for imported 1e content, and 3 more as DLC for $5 each). I found a copy on FB Marketplace for $50, still in shrink. Score! But what really pushed me over the edge was finding out about Valkyrie, a fan-produced app (PC, Mac, Android) that imports all the assets from the official app, and runs the same way, but allows for fan-created content (and includes a construction kit and examples). Well, with my set, and in English, there’s another 25+ scenerios right there. w00t. And who knows, I may try my hand at writing a scenario myself. I know Tom is down on app-driven games, but I feel like this one hits the sweet spot for just doing bookkeeping and slowly spinning out the game, and not just running it for you.