I've never played D&D. 

They always sell the books as a group of three.  The players handbook. The GM guide.  And the monster manual.

As somebody who is an outsider I've bought and skimmed 3.5 players handbook, plus some PDFs of other eras. 

Is the GM guide a "must have" book?  It seems to me that a player's handbook is really all you need to start with, provided the GM can keep it interesting with monsters and NPCs of their own creation. 

I'd say yes for just about any edition. It generally has the rules for encounter building (if you care about that) as well as magic items, various rules around traveling, etc. The 1e DMG is absolutely required reading for anyone that runs fantasy RPGs (and rpgs in general, imo) just due to the amount of advice Gygax tossed into it.

There tends to be a lot of beginner advice in the newer edition ones, but IMO it's worth having the dmg of whatever edition you are playing.

Depends on your play style but mostly the answer is "no".

I played and ran 3.5 constantly for years and the only thing I remember using the DMG for was the price of a ship. But we ran very impromptu theater of the mind games. If you use procedures and random tables, those are usually to be found in the DMG.

The monster manual is a lot more useful, especially for a game as complicated as 3.5. Properly statting a 3.5 monster is no small feat

Short answer: No.
We played 1e heavily before the DMG was released. Yes, the 1eDMG is great, but not needed to run the game. The only other edition I have run is 5e. I never did and never will buy that DMG.

Quote from: Vidgrip on July 16, 2024, 06:42:47 PMShort answer: No.
We played 1e heavily before the DMG was released. Yes, the 1eDMG is great, but not needed to run the game. The only other edition I have run is 5e. I never did and never will buy that DMG.

1E DMs guide had the attack tables. What did you do without them?

Quote from: weirdguy564 on July 16, 2024, 06:00:55 PMI've never played D&D. 

They always sell the books as a group of three.  The players handbook. The GM guide.  And the monster manual.

As somebody who is an outsider I've bought and skimmed 3.5 players handbook, plus some PDFs of other eras. 

Is the GM guide a "must have" book?  It seems to me that a player's handbook is really all you need to start with, provided the GM can keep it interesting with monsters and NPCs of their own creation. 

I would say having all three books tends to be a practical necessity. Yes, your DM can make their own Monster Stat Blocks, but there's something to having an entire book of Monsters already made for you at various different levels/CR/HD.

It's just a matter of practicality.

After that, the DM's Guides have traditionally been where the majority of magic items are detailed, and D&D tends to be a very magic item heavy game. Some of them even have some good advice on making Dungeons, encounters, ect.

But for the full D&D experience, it's best to have all three books to begin with.

Quote from: Ruprecht on July 16, 2024, 06:49:36 PM1E DMs guide had the attack tables. What did you do without them?

They were in Dragon I think...also, seems like A LOT of people were playing AD&D without the DMG for a while, even though it's insanely useful.

I'd also say "yes" you need the DMs Guide. Except in the case of the first printings of the 2000 3.0 Players Handbook which had a very abbreviated DMs Guide section in the back of the book which gave you just enough information to run some adventures.

Yes unless you want to make up all of the magic items yourself.

If you are going to run D&D; choose a ruleset or edition or clone, etc.  Purchase the DMG, or GMG; for that ruleset, edition, or clone.  Everyone should probably own at least one DMG or GMG.  (I own 3, myself.)

Then you will probably never truly need, to purchase another.  It doesn't hurt to have 1, to at least reference; from time to time.

The PHB, and MM or Bestiary; are much more necessary to run a good session or three.

Yes, you need the DMG.
There are idiots on Reddit who keep telling people no you do not need the DMG. And then complain when people make mistakes because... they did not have the DMG.

What a surprise.

A DM for 5e though needs someone to have the PHB because 90% of the rules the DM needs to know are there.

I would say it depends on how much guidance you would like for running the game.  If you are brand new to RPGs in general, it can be a big help, if you aren't familiar with how to translate the system to your current experience into the new game you're running, it can be a big help.
But ultimately no, you don't actually need it. 

You need the DMG for the magic items and envoronmental rules at the very least. The environment rules not so much. The DMG also has the NPC interaction rules.

Which explains why half the time on Reddit people complain about there being "no mechanics for interaction" because no one actually reads the DMG.

I'm so used to an RPG core rule book being a complete game that it's just weird to have D&D set a precedence for being split into three books.

Also, from what I saw it does indeed seem that a Player's Handbook is enough to play a game. 

Quote from: weirdguy564 on July 17, 2024, 08:58:33 PMI'm so used to an RPG core rule book being a complete game that it's just weird to have D&D set a precedence for being split into three books.

And that's a funny statement for me, since I started with OD&D. OD&D was the first RPG and it was divided into 3 books. I find that a single core rulebook is strange, since only the player's third of the rulebook should be in the hands of the players. I would rather that my players NOT have access to the monster information and/or a lot of the secret information from the DMG.

Quote from: weirdguy564 on July 17, 2024, 08:58:33 PMAlso, from what I saw it does indeed seem that a Player's Handbook is enough to play a game.

As a player, yes. Someone in the group probably needs all three books, but most of the players only need the PH.

Castles & Crusades is a neat example. The PH came out and we were able to play because the had access to AD&D and C&C wasn't that different. I picked up the Monster book and eventually the CKG (essentially the DMG) but didn't need them that much because I already had AD&D resources. But if I had been a first-timer and didn't have all that other material in other books, I would have jumped all over the CKG.

Honestly, I feel like the 5E DMG is junk. There are a couple of pages that I find useful, but mostly I can rely on nearly 5 decades of playing D&D to "know" what to do, and the Player's Handbook offers a huge percentage of the rules needed to play. But that's just me. I'm sure a lot of players find great stuff in the DMG and, as I noted before, someone in the group ought to own a copy.