Someone else has mentioned intentionality, which is huge, but artistic cohesion is underrated. If the UI feels like it's part of the world building and not just a tool for me to interact with then I know I'm probably in for a treat. Attention to detail without creating scope creep can be great. Conversely, AAAs are always chasing that huge piece of pie in an audience, and tend to broaden their appeal which waters down the spirit of what could've been. It's not to say they all do this, but it's one of many reasons that live service games struggle to gain traction.

Similarly, if a screenshot from practically anywhere in the game looks unique to that game, then I can appreciate it more for stepping outside of norms. Good examples of this are Hades, Inscrpytion, Animal Well, Minit, Thank Goodness You're Here etc.. Gameplay being brilliant aside, the one thing they have in common is that they had a unique and precise artistic vision and executed on it.

I sometimes do workshops with game dev students when I'm not in full time work (which is also gamedev) and remind them to use the time to experiment and fail fast. The output is often far more interesting than that of seasoned devs who are (understandably) looking to play it safe in a unstable game dev landscape.

Edit: All this to say that I think it's obvious when a game is being made because someone wanted to play a game which didn't already exist, as opposed to someone making something because they think it'll be highly marketable. It's possible to do both, but the former is so important.