I expect it's a matter of scale. Game designers are more powerful than the gods within their virtual worlds. I imagine that having arbitrary control over matter

I expect it's a matter of scale. Game designers are more powerful than the gods within their virtual worlds. I imagine that having arbitrary control over matter, energy, time and space in the physical world at small scale would qualify you as a small-scale god. At planet, galaxy or universe-scale that sort of omnipotence would qualify you as a rather serious deity - especially since it would presumably enable immortality, omniscience, etc..