Mattick’s minimal definition of a world model is a dynamics model that predicts the next state from the previous state and an action, a practice he says predates the term by a long time.

“It's just it's a dynamics model which predicts the state from like the next state from the previous state on an action and I don't think there's much more to it and if that's it then people have been doing this for a very long time without calling it a world model.”