someone mentioned physics. Which might be an interesting conundrum because an important characteristic of games is that some part of them is both novel and unrealistic. (They're less fun if they're too real)
It depends on the genre. Simulation “games” tend to love realism of simulation while providing an accelerated time. Others like you said, are more fun with plausible physics or physics that bend the rules a little bit. Sometimes, a game just about funky physics becomes a hit - Goat Simulator.
Walking/Running/Steps have already been solved pretty well with NN’s, but simulation of vehicle engines and vehicle physics have not. Not to my knowledge. I suspect iRacing would be extremely interested in such a model.
edit
I take it back, PINN’s are a thing and now I have a new rabbit hole…
