I just watched another good video by the Questing Beast (HERE).
He asks the question "What matters most in DND? and gives his 5 answers.
His list is as follows:
5 Physical Environment
4 Rules
3 Players
2 The Content
1 The Game Master
It is hard to find anything here to disagree with, and as TQB notes, the order of these shift around a bit.
As for me, I'd add a few things, what I call the 'hidden curriculum' of having a good game that has very little to do with externalities like the room or rulebook.
Here we go:
3 Buy In
By this I mean the game concept and how this is followed through. This is why early D&D was so popular and held people long enough to have campaigns - you were a party of heroes clearing out a dungeon to level up, find a relic, and save the world. I played in a year long campaign, and it was epic.
As other games grew popular in the 90s, this longform campaign became difficult to sustain. If you were playing superheros, you were emulating an episodic genre where everything reverted back to normal after the big bad was defeated. Ditto horror, where the chances of surviving and mechanisms for leveling up were absent, and saving the world was often a joke.
But the worst transgression I saw time and again was the GM who pulled a 'switcheroo' on the players and killed the game. If a GM pitches a supers game, but then sics a power leech on players to take away all their powers and hunt them down, (s)he should not be surprised when they all walk. As I have mentioned before, old school scifi games were BAD for this - promise players access to an infinite galaxy, then have them stranded on some backwater planet fighting primitives to get resources to repair their spacecraft.
TLDR make sure everyone buys into the game pitch, and follow through with it to have a satisfying game.
2 Style of Interaction
Another make or break aspect is the style of interaction of players and the GM. In teaching, we call this the 'Guide on side or sage on stage' dilemma. Does the DM handhold the players, or does (s)he sit back and riff off their roleplaying?
If the players are newbies, then the GM has to be in the driver's seat, but as the players become more skilled at improvisation, the GM can sit back and let them hand him or her story hooks to drive the narrative and keep interest high. This demands more from the GM, and new GMs can equally be overwhelmed by veteran players chewing the scenery and hogging the limelight.
To be sure, this is asking a lot of both GMs and players, which is why we should all strive to play at as many tables and in as many different games as possible to bring back skills and the consideration that allow us to match the flow of interaction at the table where we sit.
1 Game Mode
This is somewhat related to number 1, but focused more on player responsibility. This is what I call the 'Heroes or zeros' conundrum, as in some games like modern D&D promote (super)heroic playmodes, while OSR and horror games lean into characters who start as practically useless, and often remain that way.
I have seen modern D&D players try to swing from a chandelier while casting a spell and reloading a gun in a Call of Cthulhu game, and Cthulhu players meekly announcing one action at a D&D table. This mismatch really lets the air out of a game, so if you are checking that everyone has bought into to the concept, don't forget to remind them of the mode in which that game is best played.
Now, the biggest consideration, especially in light of recent events...
0 Player Safety
As you've no doubt heard, this past week the truth of the Cornell 57 and their (in)actions regarding preying on a female student have come to light. This may have come as a shock to some.
It sadly was not to me or many others.
During my MA, a senior professor constantly made lewd remarks to my female colleagues, and all of us who went to the office to protest were blacklisted and punished by lower marks and pressure to remain silent.
So higher education has a problem in its treatment of women. But so do roleplaying games.
I have personally seen a Vampire Storyteller go into graphic detail of a a female player's character being raped.
I have had a female friend ask me to come to a game and sit with her because she was afraid of the GM.
I am sure many of you have similar experiences.
About a decade ago 'safe words' and lists were a hot topic in the RPG sphere, and sadly were scoffed at by some.
Let me be clear - if you laugh at player or GM safety, you are part of the problem.
When I run a game, I always preface two things:
1) There is no rape in my game. If you get captured, you may be interrogated before you escape or are rescued, but it will never be sexual.
2) I gloss over intimate content. If you want your character to seduce an NPC, if it happens, it will be off camera.
(NB Other GMs may be fine with these things, but not me. And we all have to respect each other's boundaries.)
In my experience, games that include a diversity of genders and identities are always more interesting, and the first step in creating this kind of welcoming table is ensuring safety for everyone. But especially those who are most at risk.