So what is the difference between Basic, B/X and BECMI?

[Ariosto]

A lot of Holmes goes back to the original D&D set, such as all weapons doing 1d6. Other things, such as the hit dice and monsters' attacks, are later developments. Such "Holmes house rules" as initiative by dexterity stem from ambiguities in the seminal text. The roll to hit for magic missile spells is a reasonable interpretation of the original spell description (in Supplement I). The short combat turn is more clearly novel, although I suppose one might derive it from a combination of ambiguous usage of the term "turn" in D&D with the reference to Chainmail (but then 6 seconds would seem more likely than 10). That underworld inhabitants can see in the dark, the peculiarities of doors therein, etc., are also features of the original game.

Exploration movement rates are double those in other post-OD&D editions (including AD&D), reflecting the original game's feature of two "moves" per turn.

(I like the original scheme not only from long familiarity but also because deducting a "move" for various activities -- such as opening a stuck door or deciding which way to go at an intersection -- works in a way that pleases me.)

The mention of running at triple speed also (at least in my memory) stands out as notable, although I think AD&D made similar provision.

The simplified treatment of encumbrance got slightly complicated in later Basic sets. The Holmes version has a "rough and ready" elegance (a curious combination that seems to me quite in the D&D spirit) that stands out from the counting of coin-equivalents in both the Original and Advanced games. Consideration of just how one is carrying one's kit -- rather than a "weight" total -- gets special attention in the text (including an example equipage), and I think quite properly.

So, Holmes is in many ways an introduction to OD&D. Gygax wrote that it offered nothing of significance for owners of the little brown books, but I think that sells short the clarification of some things (especially concerning combat). An error introduced a mixed-up derivation from Chainmail that made daggers the best, and two-handed swords the worst, hand-to-hand weapons in the game -- but a similar rule (for daggers, anyhow) had been used in the Gen Con IX D&D tournament!

Overall, though, I would say that play is very similar to later Basic editions and that one might without too much trouble move on to either Expert Set (or to the Advanced game).

 

[Fifth Element]

Good responses so far, but the most important difference hasn't been mentioned yet: BECMI was the first edition of D&D I played, and therefore it is the one true edition.

Your mileage may vary.

 

[TerraDave]

We need some illustrations.

Holmes:

Moldvay

Mentzer

 

[Ariosto]

Note that the Holmes BOX cover is in full color; the book itself has a duo-chrome (black and blue) cover, while module B1's is black and green. Also, the UK edition has different illustrations (roughly same subject matter, but distinctive style).

 

[rogueattorney]

A lot of Holmes goes back to the original D&D set, such as all weapons doing 1d6.

Variable weapon damage was presented as an optional rule in Moldvay and Mentzer. d6 for all weapons was the baseline rule.

 

[Dyson Logos]

My ragging on the Mentzer nerf of thieves was misinformed.

He didn't nerf them in the Expert rules revision, he had the same skill progressions there. It was when the Companion rules revised the skill progressions that they got nerfed.

I just read the Mentzer Expert rules for the first time this afternoon.

 

[Voadam]

I read further on the Mentzer [later edit, actually meant Holmes] initiative, combat, and some of the monster sections last night.

Daggers and other light weapons attack twice in a round. Swords and such go once a round, heavy weapons like axes, flails, two-handed swords and polearms go once every two rounds. No advantages for using a heavy over a light melee weapon. Sounds like half of a system there.

Most monsters have little description, orcs are CE humanoids, goblins are LE humanoids, bugbears are sneaky CE giant goblins, hobgoblins are LE giant goblins, kobolds are dwarflike evil humanoids. What do they look like? "humanoid".

Basilisks are small reptilian creatures.

Carrion crawlers only do 8 paralysis attacks, no damage.

Djinnis are neutral and do not grant wishes, though they can conjure stuff like the later spells.

Elves are tougher than dwarves (1+1 vs 1 HD) and do more damage (d10 vs d8). Dwarves have 1 AC advantage though.

Neat system for giant rock throwing, they do damage to areas of effect and you roll two d6s, one for overshooting and one for undershooting, to see how close to their targeted area they get. Giant damage is significantly big.

Hobgoblin (I think it is hobs) elites use gnoll stats but there is no gnoll entry

Hell hounds do 1d6 per hit die on their flame breath, no limits for their breathing listed.

Horses have no attacks.

Hydras have 6 hp per HD and 1 head per HD that does an attack for d6. Every 6 damage and a head is killed, no regeneration. I really like their hydra.

Mummy rot from mummy touch slows healing down to 1/10 normal rate unless a quick cure disease which brings it down to 1/2. Mummy fear paralyzes everyone who misses a save until the mummy touches someone. I forget if they are 1/2 damage or immune to fire but they are not vulnerable to fire as they later become.

Oozes, slimes, jellies, puddings, all still really tough and deadly, most require magic or fire, many with odd specific unexplained immunities.

 

[Voadam]

Nobody advances in attacks or saves. Fighters can use any armor and get d8 HD. They can use any weapon, but all weapons do a d6 so the wizard is not worse off with daggers (fighters can use bows for further range though). Str does not seem to do extra damage. Fighters still seem the best off because wizards get their one and done spell (though they can make scrolls for 100 gp/level and one week of scribing), thief abilities won't work 80% or more of the time, and clerics only get armor, turning, and d6 HD. Plate mail is cheap enough to be bought with starting gold. Magic missile requires a full attack roll and acts like a +1 arrow. Sleep is the only big gun spell.

Charm person is also a super effective spell in Holmes, completely under your influence and lasts at least a day before a second save.

The no str bonus though makes the inclusion of the strength spell which only increases your str score very questionable.

Wizards get a huge possible gun in ranged area 6d6 fireball and cold wands. Interestingly many wand and staff things work only on melee hits, such as a sample NPC's wand of petrification.

 

[Dyson Logos]

I read further on the Mentzer initative, combat, and some of the monster sections last night.

Daggers and other light weapons attack twice in a round. Swords and such go once a round, heavy weapons like axes, flails, two-handed swords and polearms go once every two rounds. No advantages for using a heavy over a light melee weapon. Sounds like half of a system there.

This isn't in the Mentzer edition I read... Are you sure you aren't reading the Holmes edition?

I know that the 2handed weapon rule was changed from the Holmes edition (attacks every other round) to the Moldvay edition (attacks last every round). I can't imagine that Mentzer went back to the Holmes version from the Moldvay version.

Most monsters have little description, orcs are CE humanoids, goblins are LE humanoids, bugbears are sneaky CE giant goblins, hobgoblins are LE giant goblins, kobolds are dwarflike evil humanoids. What do they look like? "humanoid".

Ok, this is definitely Holmes, not Mentzer, since Mentzer & Moldvay only have three alignments, no CE or LE.

 

[Weiley31]

So I guess that means the best version of B/X would be the 1981 version for non-nerfed Thief Skills scaling and then the Rules Cyclopedia for a number of additional add ons like classes, attack ranks for demi-humans, etc etc plus whichever weapon attack rounds don't suck.