Must admit I played ridiculously few games in 2016 and listened to very few soundtracks. That coupled with a poor memory in general leads to me really struggling with this list. However, Joe's post reminded me of this one and it is truly beautiful. The soundtrack feels possibly bigger than I was expecting for the calm relaxed game it is but it is full of heart and gets quite rousing.
This one was a bit of a surprise. Took a punt on Steam without knowing what it was and the soundtrack is pretty superb. There aren't a huge amount of tracks, I think - or at least I heard the same ones frequently - but what is there creates a haunting alien mood and I found myself itching for a soundtrack. There is now one available through Steam but not sure it's available elsewhere. And with that, I'm not sure any others jump to mind but I missed most of the big ones...