Understanding Procedural Content Generation in games

As discussed in the introduction, we are refering to all the algorithms that can generate game content at runtime with PCG algorithms. A PCG algorithm may create the level design, weapons, graphical assets, musical themes, enemies, NPCs, characters' backstories, and whatever else you set your mind on. If you think about any element in a game, there is a chance that there is at least one game that attempted to generate it procedurally. But why should you?

Nowadays, PCG has become a synonym of random for the general public. Many games advertise having procedurally generated levels as a way of saying that they offer thousands of different levels that change at every playthrough. While PCG may indicate some process of causality, it is worth noting that that's just part of the PCG landscape (even if, probably, the most marketable). More properly, PCG is the opposite of randomness: it is an algorithm that very deterministically...