AI in games dates back all the way to the earliest games, even as far back as Namco's arcade hit Pac-Man. The AI was rudimentary at best, but even in Pac-Man, each of the enemies—Blinky, Pinky, Inky, and Clyde—had unique behaviors that challenged the player in different ways. Learning those behaviors and reacting to them adds a huge amount of depth to the game and keeps players coming back, even after over 30 years since its release.

It's the job of a good game designer to make the game challenging enough to be engaging, but not so difficult that a player can never win. To this end, AI is a fantastic tool that can help abstract the patterns that entities in games follow to make them seem more organic, alive, and real. Much like an animator through each frame or an artist through his brush, a designer or programmer can breathe life into their creations via clever use of the AI techniques covered in this book.

The role of AI in games is to make games fun by providing challenging entities to compete with, and interesting non-player characters (NPCs) that behave realistically inside the game world. The objective here is not to replicate the whole thought process of humans or animals, but merely to sell the illusion of life and make NPCs seem intelligent by having them react to the changing situations inside the game world in a way that makes sense to the player.

Technology allows us to design and create intricate patterns and behaviors, but we're not yet at the point where AI in games even begins to resemble true human behavior. While smaller, more powerful chips, buckets of memory, and even distributed computing have given programmers a much higher computational ceiling to dedicate to AI, at the end of the day, resources are still shared between other operations such as graphics rendering, physics simulation, audio processing, animation, and others, all in real time. All these systems have to play nice with each other to achieve a steady frame rate throughout the game. Like all the other disciplines in game development, optimizing AI calculations remains a huge challenge for AI developers.