Of course "Are we living in a simulation" is far too vague to test. The type of simulation must be narrowed down before the question can be tested. In my paper

Of course "Are we living in a simulation" is far too vague to test. The type of simulation must be narrowed down before the question can be tested. In my paper "A type of simulation which some experimental evidence suggests we don't live in", I give an example of a (very specific) type of simulation which we can easily test: https://philpapers.org/archive/ALEATO-6.pdf https://philpapers.org/archive/ALEATO-6.pdf