As a very crude example, imagine if there were "invisible walls" in our universe like many video games have. Were we to bump into one, or somehow find it, we w

As a very crude example, imagine if there were "invisible walls" in our universe like many video games have. Were we to bump into one, or somehow find it, we would then try to figure out a scientific explanation, but if we ended up with a bizarre, labyrinthine theory after trying our hardest, well just maybe we are in a simulation. You could then try to come up with how our simulation works, and then come up with tests to prove those theories. Now, in the end, if we are in a simulation, that simulation (or one of its "parents") is reality, and so effectively we are all bound by the physics of the base reality, so one could argue that there is no harsh line between our simulations' physics and reality's physics, but that's another thread ;)