Expounding on my thoughts yesterday, I realized that you can really measure most RPGs on the market in terms of their readability vs. their functionality....that is, how fun it is to read the book, vs. how easy it is to figure out how to play from that book.
Most games seem to skew sharply in one direction or the other in my experience. If you're lucky the game will be both fun to read and as a side effect it will explain the rules to you along the way. More than a few contemporary games are fun to read because they are full of exciting fiction but the moment you get to the actual rules the game turns south, becoming morbidly dry text by comparison to the effective fiction it had up to that point been tantalizing you with. A few games suck horribly at the fiction, and those are unmentionables which neither entertain nor inform you of their intent in any meaningful way....they're the $1 bargain basement/ebay specials we run across on occasion in many cases.
In case you're wondering I'd label a lot of White Wolf/Onyx Publishing content in this category: fantastic reads, and with any luck the rules will become apparent as a side effect.
Of course...I'd probably suggest a number of FATE systems for games where the reading is great but the rules exposition is a nightmare of confusion. But I am self-identified as too "traditional" to grokk FATE so whadda I know.
Games which inform the reader of the rules extremely well usually do so by getting right to the point, being brief and clear. Only a few games in my experience really do this well. Savage Worlds is (in my estimation) the pinnacle (pun intended) of such design: clear, highly focused and lighting rod-on-the-money rules with no frills beyond lots of cool graphics and suggested but brief exposition by the author to keep you learning. Other games known for such flare include Tunnels & Trolls 5th edition, B/X Dungeons & Dragons, and Call of Cthulhu. It probably helps that the game systems for each is fairly basic.
More complex systems have given it a go, usually by refining their core rules into a lite package with generally okay results; Hero Basic does pretty well at condensing the whole game into a digestible package that's not too painful to read through, while GURPS has a fantastic lite edition which while ultimately short on enough content to use on its own is still the ideal teaching tool for GURPS. Speaking of which, as complex systems go I have to commend GURPS 4E for being fairly readable (imo) if convoluted....you'll enjoy trying to learn GURPS, even if the game still has too much crunch for most mortals to handle. Hero is similar; it's a fun read even if I never properly absorb any of it all for actual play.
There are games which fail at all of the above....some quite good, but nonetheless coming up short in terms of their ability to fullly engage the reader with either prose or clarity for obscure reasons. It's a bit of a personal call on what systems fit the bill, but I have a few of my own: I've always been baffled at just why I, a guy who reads a lot of modern SF and transgenic fiction, can't stomach reading Eclipse Phase. I similarly find Numenera hard to get into despite liking everything it seems to offer. Edge of the Empire might be a fantastic system but the little symbols the game uses are hard for my brain to pronounce/reconcile so I will never know. Similarly I know I should love Runequest 6 but my nagging visual disorder which prevents me from tolerating its odd font loops stops me cold. Then there are games like Mutants & Masterminds which feels like an enormous word count for what should be a more wiz-bang get-to-the-fun sort of game. MnM desperately needs a 64 page lite version that gets to the point....
There are some games that are just badly written and maybe even poorly designed, though it's hard to discover that if you're too busy suffering in pain at the prose. I honestly label a fair chunk of the Pathfinder/3rd edition D&D body of works under this label; there's a lot of stuff out there that's just not fun to read at all, and anyone who tells you otherwise is just trying to justify their obsessive collection habits in the face of crap. Most games that fail to be entertaining or illuminating usually die or get buried....there are a quite a few out there, lingering like the onerous beasts they are, hulking in the wilds of used book shops and PDF sales events.
I happen to have a short list of what I believe are the five coolest, most smartly written RPGs on the market. These are the five games I feel do the best job of both telling you and teaching you what they are and how they work. In no particular order:
Tunnels & Trolls 5th edition - the definitive T&T, and the one most people think of when they take a trip down nostalgia lane.
Cyberpunk 2020 - Mike Pondsmith's (NOT Richard Talsorian) engaging street samurai prose made this game come to life big time, and was fully integrated with the rules. Every game he wrote was great, but CP2020 was far and away the most engagingly written, fun read in an RPG before or since, and the reason most other cyberpunk genre RPGs fail is because they couldn't figure this part about CP2020's success out.
Savage Worlds - as I said earlier, Hensley writes to the point and keeps you on target. Anyone can take the Explorers Edition and run a game in thirty minutes, or be world building in two hours.
13th Age - nestled somewhere between old school and very, very new school 13th Age is an interesting beast. It's got a huge thing going for it: the game is well written, with an engaging tone and ease of style that makes figuring out the game very easy. This is probably the only full RPG I've bought in the last year that I have read cover to cover and thoroughly enjoyed. It's only flaw is that they are taking too long to get new books out.
Call of Cthulhu - the core rules are elegant and simple; the subject matter compelling and detailed. This horror game has survived as long as it has for a reason.
And now for the Best of the Inversion, fantastic story that conveys the rules, even if by accident:
Over the Edge - in a curious inversion, the engaging dialogue teaches you how to play with little effort at all; the rest of the game is all prose and fiction about the bizarre world of OtE on the island of Al'Amarja, and that's where most people will spend their time puzzling crap out...
Blood & Smoke (or anything WoD): The Strix Chronicles - a excellent reimagining of 2nd edition Vampire: the Requiem in which every page drips with suggestions, ideas, story and character. The game is in there somewhere too, I think.
And four games I love which are fun reads but terrible at teaching their own game (or making it interesting, anyway):
Legends of Anglerre - the only FATE game I got close to understanding. Well written and makes me want to play it, but even LoA didn't quite have what it takes to explain to a FATE newb how the hell it works (or at least how you can shed old school sensibilities and embrace the structured chaos of the FATE mechanics).
Conspiracy X and AFMBE - I have always found Eden Studios' wonderful games (Conspiracy X and All Flesh Must Be Eaten) to be awesome reads but the actual rules component is dry, sterile and uninteresting. I love both games but have never bothered to run either due to the agonizing, jarring contrast of the bland rules text vs. the amazing story text of those systems.
Mutants & Masterminds - oh god how can such a cool game be so boring to read?!?!?! Is it just me? I refer to the 3rd edition, which mechanically looks like exactly what I want out of a superhero RPG, but oh my god I can't suffer through reading the damned thing.
Finally, I give Hero System and GURPS 4E a pass, because I've learned (and run) both albeit with a strong desire not to devote more time to either game in the future without lots of pre-made stuff to cut down the "work time" it takes to make either system function.
