Spelunky by Derek Yu

First up is Boss Fight Books's Spelunky. Other than being one of the best games OF ALL TIME, what drew me to the book initially was the promise of any insight into the design of its procedural levels and systems. The secret sauce of Spelunky is its random level generation design and the possibility space afforded by its many deliberate system interactions. Much like in Due Process, the game wants the player to master their understanding of the game's underlying systems and interactions, rather than having them rely on rote memorization of level layouts.

Our game tends to have small levels due to the need to mitigate information overload while planning and to keep rounds short. To provide varied levels which demand complex plans, we need versatile terrain which can interact with other pieces of terrain to provide interesting scenarios. The golden idol traps in Spelunky's mine level are an example of how the positioning of interesting terrain can provide a lot of depth to otherwise simple levels. Have a thick wall blocking off a desirable room and not enough bombs to gain entry? Have an angry shopkeeper lurking near the exit? Great. Steal the idol and trigger the giant boulder trap to rampage down through the level and destroy everything in its path. Just be careful it doesn't destroy a sacrificial altar, crush a damsel in distress, or even kill you in the process.The list of interactions goes on and on, but the idol trap serves as a great example of how the game's systems are made up of all these somewhat generic "puzzle pieces" that fit together in ways that create interesting scenarios and strategies.

One of the closest analogs DP has at the moment is it's electrical objects system and how shutting off the power in the level leads to potentially interesting trade-offs. A plan where the attackers turn off the lights to blind the defenders, but consequently power down the automatic sliding door (which blocks off access to a room), is the result of our "puzzle pieces" fitting together in ways that create interesting situations.

While the bits about level randomization and systems design are probably the most relevant information here, this book is also a great overview of game development and how iterating on a game over many years ultimately tends to lead to something worthwhile.