This is one where lots of people will have very specific definitions. They believe in a specific god(s), and since they believe that only that/those one(s) exist, their definition would exclude everyone else's idea of god.

But if we look at what's common among the gods of different religions, and even among atheists and agnostics, there's a few qualities that seem to be pretty consistent:

• Created the universe
• Cares about what's happening in the universe, specifically life like us
• Can change the universe and our lives

Whenever I come up with a new definition, the first thing I do is try to find counter examples that wouldn't work. So, let's imagine a situation where our universe is a high school science project by some alien, when would we consider that alien to be "god"?

• If we were an accident - let's say the goal was to make a bunch of fission reactors (i.e. stars) and we're just the scum the showed up on some of the leftover rocks. Then that alien isn't god, they didn't try to make us, they don't care what we do, and they're not interacting with us at all.
• We're a simulation, but it's like a movie. The alien kicked it off, and now it's just running. Maybe some people would want to consider the alien that started everything god, but even if it's watching us specifically, if it can't do anything about what's happening, that wouldn't seem like a god to most people. It would just be a different kind of creator we haven't really thought about much.
• If we're in a simulation and it's like SimCity. Or maybe this is like a zoo or nature preserve. If there's some alien that created this, is paying attention to us, and can make some interventions (maybe they kept the asteroid that killed the dinosaurs from wiping out everything for example), then that would be a god to most people. Even if it's not like anything in any religion, and it's not like anything that anyone's really considered, we'd probably want to call it a god because it meets these conditions.