Quite complex but great book from Ernest Adams and Joris Dormans about game mechanics/game economy design.
Another great game design course from Ian Schreiber about game balance. Content is very useful for beginners, but even more experienced designers can find some parts interesting.
Great theoretical game design book with the creator of Magic: The Gathering Richard Garfield among the authors. Very useful, if you’re interested in deep knowledge about gameplay and different gameplay dynamics. The book has very complex language and might be hard for beginners.
Game design book about emergence phenomena in games. Might look outdated for now, but the topic is quite rare and interesting.
Classical book from psychologist Mihaly Csikszentmihalyi about ‘Flow’ state, one of the main components of the gameplay experience.
GDC lecture from Sid Meier about his definition of gameplay as “a series of interesting decisions”.
GDC lecture from Sid Meier about the psychology of game design.
Great lecture from Mike Sellers about game systems design.
GDC lecture from Henric Suuronen about the design of great gameplay loops. This lecture focused mainly on social games, but principles can be useful for many other genres.
Lecture from Magic: The Gathering creator Richard Garfield about game balance.
Another lecture from Richard Garfield about luck in games.
Design in Detail: Changing the Time Between Shots for the Sniper Rifle from 0.5 to 0.7 Seconds for Halo 3
First lecture (GDC 2010) about game balance in “Design in Detail” series from Jaime Griesemer.
Design in Detail: Tuning the Muzzle Velocity of the Plasma Rifle Bolt on Legendary Difficulty Across the HALO Franchise
Second lecture (GDC 2011) about game balance in “Design in Detail” series from Jaime Griesemer.
Design in Detail: Identifying the Seemingly Insignificant Decisions which Determine a Game’s Ultimate Success
Third lecture (GDC 2012) about game balance in “Design in Detail” series from Jaime Griesemer.
GDC lecture from George Fan about Plants vs. Zombies tutorial.
GDC lecture from Wyatt Cheng about Blizzard approach to iterations in game design.
Casual Connect lecture from Amy Jo Kim about innovative products creation and habit loops.
GDC lecture from Amy Jo Kim about designing of cooperative games.
GDC lecture from Amy Jo Kim about designing of Meta-Game.