Well, the statement is a bit deceptive, since ACKS is a simple game. Just because the books are filled with domain management rules does not mean the "core game loop" is huge. There is no real difference between ACKS and B/X when you are playing at the table.
Can't we play Old School Essentials and have the same game, just with fewer pages? While OSE does a "5E replacement" perfectly and gives you tons of character options that mirror that game (Tieflings, Dragonborn, etc.), ACKS is a better game if you want greater detail inside your character. OSE characters can feel "too basic" without an add-on, such as Into the Wild, and the basic fighter is a bit plain and uninteresting without a few optional rules printed in fanzines.
And given the "game play loop" in OSE and ACKS is identical, I will go for the game with the greater level of depth each time. Unless I have players wanting those 5E race options and that D&D 4E style world, ACKS II will be the more in-depth game with the better and more satisfying characters (without GURPS in the discussion, and if the players wants a d20 game).
In ACKS, you get the "real fighter." The game does not go overboard with layers of extra detail, but you get the best to-hit, cleave, and a flat damage bonus that goes up as you level. All characters gain proficiencies, and this skill system defines the game just like a feat system did in 3.5E. There is a chart laying out which ones you get on which level in each class, and also, each character gets four "training slots" available with extra study.
ACKS does have class design, and is race-as-class, so if you really wanted that Dragonborn or Tiefling you could develop a custom class in ACKS for them. It is not that hard. They have special ability lists for custom race-as-class options pages long in the Judges Journal.
Without having to add Into the Wild, the Carcass Crawler zines, or any other optional rules to the game - you have a solid core system that does not need tweaking and modification. In fact, ACKS II is the second edition of a game that has been play tested for over 10 years, so the rules are solid and work extremely well - in everything from characters to domain management. ACKS II is just about as solid of a game you can buy, with nothing else needed, no list of special mods, and you are not explaining your custom hacks to your game to anyone.
You are not buying third-party fixes or Kickstarter domain-play rules that weren't tested and shipped broken. This game is tested and works, and you don't need to keep spending money to constantly repair the game like you do in 5E. Playing basic OSE is fine, but if you want better character depth and classes with some meat on the bones, and you do not want to mod the game, ACKS is by far the better choice.
If I were playing with more casual players, and "small books" were a requirement? Sure, I would choose OSE or Shadowdark for such a group, we need to play to the audience. I am not forcing a game the size of encyclopedias on a casual gaming group unless they were really into it.
For a years-long game that goes into domain management? ACKS will deliver the better experience for an epic-scale campaign, and you won't need to keep spending money to fix the game or add options along the way. As a "complete and well-tested" game, ACKS will beat out every other B/X-based competitor.
I added a list gadget to the sidebar for ACKS focused YouTube channels, so we can visit them regularly and support ACKS creators in the community. Anything we can do to get awareness to our creators is a good thing.
One of the best videos on ACKS is out recently, and it touches an issue which I wrestle with. Is ACKS II too intimidating? Do people bounce off the game and never return, fleeing back into the cave for easier systems, such as Swords & Wizardry and Old School Essentials?
I bounced off and this does not seem like thoughts in isolation.
But please, this is an ACKS II YouTuber! Let's watch this video, like and subscribe, and support our content creators! We need to lift up those who give us great content, so the best way is to watch and support the people who spend the time to make things for the game we love.
At its core, ACKS is like any other B/X system. All the core components are in place, and the underlying "game engine" is no different than what we are used to. This game plays exactly like OSE, how could people bounce off?
I am betting this is the expectations we put on ourselves. We want to be instant experts, rapidly proficient, and "get our fix" within the first five minutes of opening a book. We put these expectations that "if we own the book, we are an expert" and the is the fallacy of "bought knowledge."
If all you are doing is playing ACKS II with basic characters, fighting orcs in a dungeon, and grabbing bags of gold, then we are playing the game just fine. There is no need to go into the local ruler's tax structures, kingdom influence, random seasonal events, influence factors, trading caravan rules, naval combat, stronghold construction, and all the other rules in the book.
Those rules are there is we want to explore them, but the game is fine without them.
If all we want to do is play "Keep on the Borderlands" with ACKS II, there we go - it works and we are just fine. But what about all those other rules we aren't using! We aren't playing the game right!
Here is another secret.
The "extra rules" in ACKS II are the game's future-proofing. These dominion, trading, stronghold, kingdom management, and other rules for every subject are there to save you money on an endless stream of grifter Kickstarter projects that poisoned the well of games like 5E, and are doing it for Shadowdark.
Except, of course, for the Autarch ones! Those are cool and we always jump on the premium levels, since we support what we love. Click on that link above since we need that Elven book! Get notified on launch, and then you can actually play a game where elves conquer land, grow their civilization, and build their own dominion. Elves in ACKS II don't always need to be "dying and in decline."
It is your choice, to be honest.
But we will not need much else to play this game, and it "comes out of the box" future proof and complete. However, we do not need to use all those rules, or even all the "how to play" rules in the Judges Journal. We don't! Stop hamstringing yourself and running back into that cave!
Those rules are there for later, just like algebra and calculus are there for later in mathematics. And like math, not every problem is geometry, so put away the protractor when all you are trying to do is tell an adventure story of beating up orcs and goblins.
Stop. Being. A. Perfectionist.
You don't need to master the game to play it. In fact, going in with that expectation will lead to self-defeat. You will never master the game since you will get intimidated, disappointed, and give up early. Don't be like the 90% of college majors who give up before they ever achieve their dream.
Be one of the 10% who stick it out and find true happiness as mastery comes after months, or even years, of study and effort. The journey shall be well worth it at the end.
So pick up that copy of B1 In Search of the Unknown and get your heroic, vaguely Mediterranean, suntanned butts in there! I will give you a "free pass" to ignore 90% of the ACKS II rules, and just use the characters, combat, equipment, and magic chapters! In fact, 90% of those chapters you will just skim and maybe use later. Just roll up some level one characters and go.
Most of pages 100-200 are lists of gear, spells, and skills. This is just "find what you need and go" so this is not "actual page count needed to understand the game." Pages 263-314 for the Adventures chapter is what you want to focus on, and the best parts are 263-271 for dungeon delves, and 288-309 for combat. So, the core of the game that "makes it like B/X" are thirty easily understood pages, and since this is "just like B/X" those will go quick, and you already know most of this stuff.
In fact, print these delve and combat pages out, staple them together, and toss that to your players.
Just play with chapters one through six in the Revised Rulebook. This is your "basic set" and the rest of the book is dominions, voyages, and mass combat. For B1, we don't need any of that! Sorry, that is all fluff and "saving you money on Kickstarter" stuff.
Most of the combat stats can be used as is. Even the old descending AC values in B1 can be converted easily (as per the System Compatibility Guide):
BX, BECMI, LL, LOTFP, or OSE: AC = 9 – Original AC
Do we want to pull in the intimidating Judges Journal into the mix? All you need to learn is the three pages of dungeon delving rules on pages 35-37. Three pages out of nearly 500! The wilderness rules that come right after this are mostly encounter tables, but also save those for our "expert set" and for B1, we will not need them. If you find magic treasure, maybe flip to the magic item chapter. The rest of the Judges Journal? Guess what, "saving you money on Kickstarter" stuff again.
The Monstrous Manual? Flip to a page and use a monster in it. I doubt you will need more than a dozen monsters here, if even that since most you will just use "as is" from B1 directly.
It is easy to see those huge books on the shelf and feel like you should reach for Old School Essentials instead. ACKS II is so comprehensive and complete that it looks far more complex than it really is.
But flip through the tables of contents of the books, and ask yourself, "What do I really need to play?"
Most of the book is a catalog of choices of classes, skills, magic, and gear.
Very few pages are "actual rules" for "basic adventuring."
A good 70% of the books are domain management, and not needed for the basic game. 10% are wilderness and voyage rules, and can be considered "expert" rules. About 20% of the pages are all you need to play, and most of those are just "lists to pick from." That last 5% of the game? Uh, those are rules pulled from B/X. You already know those.
Understand the classes, combat rules, and turn structure to exploration. Those are your "Ten Commandments" of playing ACKS II. And yes, that is my Bible. Gamers of Faith should be proud of their beliefs and not hide them, and that book sits on my shelf right beside ACKS II (and GURPS). The Bible is the best "rule book" ever written.
And those few sections of ACKS II are all you need.
When you are done the adventure, then you can start taking over the land in B1 that "Rogahn and Zelligar" built this dungeon of madness on, and take on those "barbarians of the north" that those two fell to. Basic D&D, AD&D, OSE, S&W, Shadowdark, and all these other "flee back to the cave" games don't give you the rules you need to play "the rest of this adventure" but ACKS II does.
And ACKS II saves you a lifetime of random Kickstarter money since it comes with "batteries included."
