If you'd told me this was a forgotten Sierra classic from 1994, I would absolutely have believed you--the literal only thing that would have tipped me off is the length. The environments and character art just perfectly capture those classic sci-fi adventures like Beneath a Steel Sky (including the robot sidekick!) and Travis's voice acting has such warmth and character to it. It plays very smoothly too, not to mention that crisply implemented pixel art that's so difficult to do in Unity. I can't believe you did everything except the voice acting--you must be a rare polymath!
For things I would have liked to see, really all I can think of is that it would have been fun to have a more distinctive-looking monster, but that's really like being served a perfectly-cooked souffle and asking why it doesn't have a cherry on top.