Let me reply to that we another example: If you fly an aircraft in GTA you are not doing a million-core-hour direct numerical simulation of the air flow around the jet. That doesn't mean it's not cool and playing with simplified models might still allow you to study the dynamics of 2 on 2 aircraft fights, but it is not the same as a physically self-consistent simulation starting from basic principles that we understand.
Another example to illustrate the difference between "physics based and good enough" to "accurate but expensive" would be the algorithm by Jos Stam in a paper title "stable fluids". It is fast enough to run real time fluid simulations e.g. for water in a computer game, but is very dissipative, i.e. it removes small eddies. So while a ship moving through water simulated with that algorithm is going to LOOK great, you will get a totally wrong and inconsistent estimate of the drag on the hull. Not something you care about for a computer game, but something that might change your results if you try to do science with it.
Another example to illustrate the difference between "physics based and good enough" to "accurate but expensive" would be the algorithm by Jos Stam in a paper title "stable fluids". It is fast enough to run real time fluid simulations e.g. for water in a computer game, but is very dissipative, i.e. it removes small eddies. So while a ship moving through water simulated with that algorithm is going to LOOK great, you will get a totally wrong and inconsistent estimate of the drag on the hull. Not something you care about for a computer game, but something that might change your results if you try to do science with it.