This isn't legal advice, it's a map of the question so you know what to actually ask a lawyer if your game's release depends on the answer. And for most indie games, it's worth understanding the shape of the issue even if you never need to hire anyone.
The current general position
Guidance from copyright offices in several jurisdictions, including the U.S., has held that content generated purely by an AI system, with no meaningful human creative input beyond a prompt, generally isn't eligible for copyright protection on its own. A prompt alone isn't usually treated as the kind of human authorship copyright law protects.
Why this rarely stops anyone from shipping
In practice, almost no shipped game consists of untouched raw AI output. You arranged the assets into a specific level, wrote the surrounding code, made editorial choices about what to keep and cut, wrote the dialogue around the generated art. That human arrangement and selection is very likely what earns the overall work copyright protection, even where an individual underlying asset, taken in total isolation, might not be independently protectable. The game as a whole is your creative work; a single unedited AI image inside it might not be.
The genuinely risky scenario
Where this gets sharp-edged is if a competitor takes a raw, unedited asset straight out of your game, one you generated but didn't meaningfully modify, and reuses it in their own project. Because you may not hold enforceable copyright on that specific unmodified asset, your recourse there could be narrower than you'd assume, and it's the scenario worth actually asking a lawyer about if a particular asset is central to your game's identity.
The practical habit that lowers your risk
Treat AI output as a starting layer, not a final asset, the same editorial and modification pass covered in the AI art piece on this blog does double duty here: it makes your art look less generic, and it strengthens the case that the final asset reflects meaningful human authorship. Two problems, one habit.