You’re ignoring the possibility for shortcuts. Half-life 2 ALSO simulates the sun! It simulates it as a spot of light in the distance in the game. Similarly, the gravity and friction and motion simulation is hugely simplified compared to reality. If the sun works the way it would work in what we understand of physics, it would be extremely complex. But the same doesn’t hold if it’s a simulation.
You’re ignoring the possibility for shortcuts. Half-life 2 ALSO simulates the sun! It simulates it as a spot of light in the distance in the game. Similarly, the gravity and friction and motion simulation is hugely simplified compared to reality. If the sun works the way it would work in what we understand of physics, it would be extremely complex. But the same doesn’t hold if it’s a simulation.