[delinka]

You assume that our [observable, hypothesized] universe isn't a pittance of matter and energy in a larger universe. Suppose your Conway's Game of Life simulation gained what it considered sentience, and with this sentience contemplated whether this world it inhabits was the universe or a simulation. Now suppose that it deduced that it would take universes of energy to simulate its own universe. Well, it'd be right.

That doesn't mean it's not.

[tehwalrus]

Indeed, if the D&D universe is the real one, we may all be in some elven wizard's toy universe, with "simple" rules and no magic, where she goes to meditate... I did try to caveat in my original answer.