Since the creator won't admit it's AI, I'll point out some of the easy gotchas. One of the telltale signs of generative AI is inability to spell. It may get close to a word, or a symbol, but usually its not quite right. It's also terrible at repeating patterns and you'll often find irregularities in the pattern.
Ex A) Why does the left striped caution tape look different than the one on the right? A human would probably just copy/paste and rotate the same texture. Another texture in the game has a correctly spelled RADIOACTIVE sticker that looks almost identical, so why is this one misspelled "RADIOICYNE"?
Ex B) Same thing here with the font. It's close, but clearly not how any human would make it without very specific intent that doesn't seem to be there.
Ex C) You might have to zoom in on this image, but some of the pigs have snouts for eyes, and multiple nostrils or deformed snouts. Again, a human would have to put intent behind a design like this, and it doesn't seem like there is one. "RADIOICYNE" pigs that grew snout eyes? There other other pigs with faces as you'd expect, so you would think they would all follow that pattern.
Ex D) The models are odd, specifically the base platform. There are several little planes, disconnected to the model that shouldn't be there. How did they get there? Why would a human build it like that? The air conditioners(?) have meshes that look like the normals are reversed where it is black, or the texture is clipping into another part of the mesh. The textures don't really make any sense if you look at them long enough, suggesting that they are probably AI generated. Why does only one of the four corners of this platform have a pig foot with an eye on it? Seems like a messed up pattern because there is no clear intent why it would be like that. Best case scenario is a bad photogrammetry scan/generation. But if that's the case, how was it generated?
Ex E) Here is the title art from the creator's other game. None of the text or symbols are legible. Everything in the background layer looks like classic AI generation. Why is the line of buildings on the right floating into space while the majority of them are on the ground? The rope kinda just disappears behind the arm. The hands make sense at least. :)
I'd be happy to eat my words if the creator could show some proof of how the assets were made, or the title art. I'm not trying to hurt anybody's feelings, and won't hold it against the creator. I just think its dishonest for the creator to say they created everything. This was also a good learning opportunity to help spot some generative AI for the unfamiliar.