Fourth Player Theory of TTRPG Design

Who are you actually designing for?

A couple weeks back, I saw a poll on a large forum filled with hardcore TTRPGers. It asked how often they played. It turns out, compared to the results I saw when I worked on D&D, they barely played. Most played monthly or less, and only about a quarter or so played weekly. D&Ders would mostly play once per week. Another chunk played multiple times per week, and a chunk of about equal size played monthly. Those hardcore folks were rank amateurs to the mainstream normies rolling d20s and casting magic missile.

That poll brought back to mind a theory of TTRPG design I used in working on 5e. It’s called fourth player theory, and it’s a design guideline that says:

“A group will play your TTRPG if their fourth most dedicated member agrees to.”

TTRPGs are by nature group activities. You can play a TTRPG by yourself, but the typical player wants to play with others. In my experience, a group breaks down like this:

• The DM is pretty heavily into the game. They own the core rulebook, a bunch of dice, and probably another book or two.

• One player is hardcore. They own the core rulebook and maybe a player expansion.

• Another player is interested enough to buy the rulebook and sometimes even reads parts of it.

• The next player, our critical fourth player, might eventually buy a rulebook only after a few campaigns. They won’t read it for fun but will use it to build a character. They love playing the game, but they aren’t interested in learning it. The other players handle the rules for them.

The trick is that in terms of engagement, player four might be the most ardent participant. They show up for every session. They love playing. But they’re here to play, not read rules.

That’s the player you need to convert. If that player doesn’t want to shift to a new game, the group won’t. Maybe they’ll do a one shot, but if the rules introduce static they are out. They are here to pretend to be an elf or to burn down the town library by accident while rooting out a Cthulhu cult. They are not here to learn how talents interact with the skill system or the cases where rolling two sixes does not mean a critical success.

You can tackle the fourth player problem in a lot of ways. An obvious one is to make your rules easy to use and transparent, so that learning them is a snap (especially if the DM can handle them, though a complex or cluttered character sheet is a death sentence). You can also hook them with a great premise linked to fantastic art, as these players can get excited about the vibes around a product. That’s partly why D&D used annual stories with Hollywood-style pitches during the Golden Age of 5e. That stuff is catnip for the fourth player if you can get it right.

Most games ignore this principle. I think it’s what distinguished 5e from previous editions. It’s a double-edged sword when it comes to mechanics, because the game that makes the fourth player happy might lack the depth that players one through three want. Balancing those two audiences is what separates a niche game from one that really breaks out.

Obviously I think that 5e does a good job with this, but its lessons aren’t all great (the game has a strong root in materialism in its combat system, but most fourth players don’t engage with the rules outside of character classes, so it doesn’t trip them up). It’s also an argument in favor of character classes, as the fourth player needs to learn a few class features and is good if the rest of the group handles core rules.

Free League’s Alien TTRPG is another great design to look at. Its cinematic scenarios are particularly great in this regard. Shadowdark is another one, though I think it might leave players one through three cold unless they are really committed to an OSR style of play. Mork Borg and its descendants are also worth looking at here. The art and writing in those games shows how powerful tasty vibes are in hooking the fourth player.

Obviously if you’re designing for fun or with a personal vision in mind you can ignore this, but if you want to sell a TTRPG at scale you need to design with the fourth player in mind.