You may have heard of some older theory called "GNS" and "Creative Agenda" which talked about "why we play" and which aesthetic principles were important to the players.
In GDNS, the talk is instead about how we play and about what even constitutes play.
Overlap with GNS "Technical Agenda"? Heck yes! And that's fine!
Because getting on the same page about which techniques are kosher and which are iffy is SUPER IMPORTANT to us humans! It's the outside-in approach to finding common value ground!
Now what is GDNS? It stands for Gam, Dram, Narr and Sim!
In Dram, one or more of the participants is a super talented story writer in the attic and pre-writes a very interesting story that the group can then bring to life and experience in full color at the gaming table! This could be a GM writing "First the players are gonna do X, then they're gonna do Y, then they're gonna do Z" style notes before play, this could be a player writing ten pages of backstory for their character which is going to be recounted closely during play!
In Narr, one or more of the participants is a hippie! They want to encounter choices that would be meaningful diegetically, such as "Should the hard-working cop abandon her family in order to protect them?". The most important life dream of a Narr hippie is that a very unexpected story is created during play that can then be retold to your hippie friends at the next con!
In Gam, one or more of the participants is a power-hungry munchkin! They want to encounter choices that would be meaningful mechanically, such as "Should the hard-working cop equip a +1 one beastmaster sword or a x3 mod lightning round gun in order to best protect her family?". The most important life dream of a Gam munchkin is to test their own might! To face challenges and bravely stare them down with their lifelong journey of system mastery!
In Sim, one or more of the participants is a curious individual! They want to examine the clockwork of the system, how will the little ants in the sandhill move around and what will happen when they collide! The most important life dream of a curious and imaginative Sim daydreamer is to see their doll's house come to life and see the dolls do What They Would've Done Really. If they were alive. But with spaceships.
Wait, there's more!
These four corners of the GDNS quartet may sound like mortal enemies. But that's not the case, they are the best of friends!
Here is the official poster for the GDNS kumbaya of FRIENDSHIP:
But not everything is a paradise in the GDNS land!
Here is the official diagram of the official GDNS Hatred Parade of Eternal Enmity: