On my first post on the subject of playing Dungeons & Dragons for free, I stuck implicitly to living systems; that is, the current editions of games in print and supported by their publishers. For D&D this means Dungeons & Dragons Fifth Edition (5e), published by Wizards of the Coast (WOTC), and Pathfinder, published by Paizo.
My advice was to stick to the free materials, which for 5e the is Basic Rules, available as a free PDF, including DM guidelines, and the free content on D&D Beyond, which includes the whole of the Systems Reference Document (SRD). I neglected to discuss Pathfinder, which also has a lot of free content available to download. And as these two systems are the Big Beasts of fantasy role-playing, they are likely to be the first ports of call for new gamers.
The major drawback of sticking to this free content is that you won’t have access to the “complete” game. For example, the Basic Rules pdf limits players to the four “core” races (dwarf, elf, halfling, and human) and the four “core” classes (cleric, fighter, rogue, and wizard), with one customization path or “archetype” for each (meaning it isn’t really customization at all). D&D Beyond’s free content gives you access to all the races and classes in the Player’s Handbook, but sticks to one archetype for each class, and only a limited selection of backgrounds and feats. While feats are optional for 5e, backgrounds are actually an essential part of character creation, so this is a significant omission.
There is, however, a way in which you can play a “complete” version of D&D (that is, have access to all “core” game mechanics) for free: play a retroclone.
For those who have never heard the term, a “retroclone” is an independently-produced ruleset which recreates an earlier edition of a popular role-playing game, usually with some refinements or additions. Pathfinder itself could be considered the first retroclone, as it was produced by Paizo (at the time a much smaller company than Wizards of the Coast), and recreated Dungeons & Dragons 3.5, which had recently been replaced by Fourth Edition.
Because retroclones make use of the existing Open Gaming Licenses, any changes to the original rulesets are made less for copyright reasons and more for the preferences of the producers and their intended audiences. For example, many Zero Edition (or Original Dungeons & Dragons) retroclones have much clearer wording and organization of the rules than the original 1974 game (which was notoriously opaque). Another common innovation is to allow ascending armour class (in which a higher armour class is better) as the norm or at least as an option. There have been several ways things like stats, abilities (and “skills”, if they are used), combat, etc. have been handled in D&D over the years, and the author(s) of a particular retroclone tend to pick their favourite one or suggest a personal house rule as the standard option.
Some retroclones are as pricey as the current versions of the game. Astonishing Swordsmen & Sorcerers of Hyperborea, a 1st Edition Advanced Dungeons & Dragons retroclone, retails for $70, although this is excessive, and mainly due to artwork and binding, still, many popular retroclones, such as Labyrinth Lord or Lamentations of the Flame Princess will cost you at least a little cash, even for just the pdf. [EDIT: Both LL and LotFP are available as free, text-only pdfs (no artwork).]
However, if you divide Old School D&D into the three categories of Original, Basic, and Advanced, there is at least one free retroclone for each.
There are several “Original D&D” retroclones. I discover new ones all the time. My personal favourite remains Matthew Finch’s Swords & Wizardry, which comes in four versions, all of which you can get for free. White Box, my absolute favourite RPG ever, is a clone of the original three booklets in the first ever printing of D&D. (Unlike that original printing, White Box makes perfect sense and is a pleasure to read.) This version is no longer available on the Frog God Games website, as it has basically been replaced by Swords & Wizardry Light, which is also free, and pretty much the same game except it allows the Thief class and only has rules for levels 1 to 3. The next step up is Swords & Wizardry Core Rules, a close second to White Box, in my opinion. This version clones the rules as they stood after the Greyhawk supplement was published in 1975. It is, on balance, probably the best version of the game. It has plenty of options and mechanics, but not so many that it becomes, well, Pathfinder. And finally, there is Swords & Wizardry Complete, which clones everything you would find in the original rules, all five supplements, plus anything you might have pulled out of issues of Dragon Magazine. Personally, I only own this one for the monsters. You can never have too many monsters. I would never give this many options to the players in an Old School game.
Swords & Wizardry is, in fact, so popular that it has its own “clone”, White Box, by Charlie Mason, published by Seattle Hill Games. The pdf of this is also free, and could be a good alternative if you want to play a White Box clone but don’t want to play Swords & Wizardry Light.
Then there is Chris Gonnerman’s Iron Falcon, also free as a pdf, still available and supported, and more complete than either S&W White Box or S&W Light. It does include things like the Thief and Paladin classes, and tons of spells and monsters, so it is probably more comparable to S&W Core or Complete, but unlike those games, it includes some free adventure modules, which can actually be played with any OD&D retroclone (or even the “real” OD&D), with little or no modification.
When we talk about “Basic D&D”, we usually mean either the early 80s boxed sets (called Moldvay Basic after the editor of the Basic Set – again, levels 1-3 – or B/X because I it contained only the Basic and Expert rules) or the later BECMI, which stands for Basic, Expert, Comnot panion, Master, Immortal: the six sets of rules that take you from levels 1 through 36, and eventually to a godlike status that transcends character levels.
I don’t know of a BECMI retroclone (which isn’t to say one doesn’t exist, just that I don’t know about it), but there’s a very popular free B/X clone, Basic Fantasy, Chris Gonnerman’s more well known game. If you’ve heard of one Old School retroclone, chances are this is it. Everything for this game, including lots of adventure modules, is available as a free pdf, and even the print versions are dirt cheap. [EDIT: As above, Labyrinth Lord is also free in an artwork-free pdf.]
And finally, there is OSRIC (Old School Reference and Index Compilation), a 1st Edition AD&D clone, also by Matthew Finch, and also free.
So if you’re willing to go Old School, it is definitely possible to play D&D for free, without sacrificing any of the core options or mechanics, and you don’t even have to homebrew your own adventures, thanks to Chris Gonnerman!
I fully expect that a lot of readers will not be pursuing these options, however. One reason is, none of these games are (or, legally, could be) branded Dungeons & Dragons, and I expect that makes a big difference to prospective new players. Make no mistake, all of these games are Dungeons & Dragons. There is nothing about them that does not ring true to the authentic D&D experience. But just as audiences rejected the “imposter” Uncle Fester in the first Addams Family movie, a lot of players might reject these games (even though, like Uncle Fester, they turn out not to be imposters after all). If you get your friends psyched up to play D&D and then whip out a pdf of Swords & Wizardry, they may feel they’re not getting “the real deal”.
Of course, Pathfinder solved this problem, mostly by tacitly allowing their customers to call their product “D&D” colloquially. The one time I played Pathfinder, it was because someone asked me if I wanted to play D&D. I only found out they meant Pathfinder after I had already said yes. And check out this video series in which they are clearly playing Pathfinder, but frequently call it “D&D”.
But the major stumbling block will be that all these retroclones are exclusively Old School, and therefore might not appeal to gamers whose expectations are informed by Modern D&D. If you were inspired to play by watching Critical Role, you might be disappointed that you can’t play a “goliath barbarian” or a “tiefling bloodhunter”. If you were intrigued by stories you heard from Pathfinder players, you may feel let down when you can’t be a “kitsune alchemagus death priest” or whatever OP bullshit they allow in that game.
And that’s perfectly understandable. There are a million ways to play D&D, and the game is broad enough to accommodate everyone’s fantasy. But if yours can fit the Old School mold, don’t overlook these retroclones as a way to get a memorable gaming experience for hardly any cash.
[EDIT: If you are interested in a more complete list of retroclones, visit Tenkar’s Tavern (you should visit it anyway, as it’s a great blog).]