Content follows form

Form: the essential nature of a thing as distinguished from its matter

For games, this would mean the context the game is in and the structure and rules (nature) that follow from it. For example, the free to play (F2P) model. It is a form of game that is obviously free and relies on ads (or microtransactions) to make money. This is not achieved by just adding it to existing games, the F2P games are completely designed around them from the very start, making sure they are as effective as possible. They’ll try to pull you in, keep you engaged and try to keep you playing for as long or frequent as possible. The more you play, the more ads you go through and the more money the game makes. In other words, the content (game based around ads) is entirely determined by the form (F2P model).

This form of game creates an entirely different relation between the designer and the audience. It becomes less about offering something valuable and more about exploiting them. The F2P games that are successful at this, are what you could say good pieces of design. They solve the problems within their constraints/form really effectively.

Now to make this more of a tip: be aware of the form your game is in. Is it a paid game, F2P, subscription based, AR, VR, Steam or console game? Each of these has inherent constraints which tends to determine what the most effective design goals are. For F2P games, that tends to be keeping you in the imaginary treadmill, for other forms its something different. Take this into account right from the start so the design goals of the game align with its form.

For more, be sure to watch: The medium is the message by Jonathan Blow.