Thank you! There are a couple of theories that have really helped such as Flow Theory and Self-Determination Theory. There is also player archetypes by Bartels taxonomy and an updated version from the Quantum Foundry, however the Quantum foundry ignores a lot of other game archetypes since it’s a survey with 98% male (so the only type of social games that they consider are RPG type of games and ignore cozy games and visual novels).
GDC is good but sometimes the talks don’t go into theory and the videos can be too long. Indie Game Clinic (IGC) is really good for finding literature and understanding game dev theory as the guy who runs it is a game dev professor. Jonas Tyroll is also good as he combines Game dev theory with application as he has made the game Thronefall which got 10k reviews.
For books I recommend starting with The Design Of Every Day Things as it is not only good for game dev but general design.
IGC recently made a video showing the different areas of game dev theory and honestly focusing on any area will help with game dev linked here:
For me I am planning on reading Carl Jung’s archetypes to get a better understanding of what players like in a game as I feel that Bartels Taxonomy and Quantumn Foundries theories are too broad.