I feel like you achieved the atmosphere you were going for, so nice job with that! It could definitely work as a backing track in a game, although the only thing maybe getting in the way of that for me is that it feels like the piano and other meliodic parts play at quite loud and "forceful" dynamics (especially middle and end of the piece). A softer approach might blend in more in the background of the hypothetical game, but could just be my own preference! 

This makes me feel things

I think the bass is really good in this song. it is deep and atmospheric. Sometimes it feels like the melodic instrument is playing too similar of rhythms and notes throughout I think. It's a bit hard to explain but it sticks out as an instrument and because of that it's more noticeable when it feels like it's playing the same rhythms and notes. 

The best part is when it's the piano alone as it feels like it's mixed more effectively.

Love the vibes. I know how hard it is to make a track long without making it repetetive, but I think you achieved it. : ]