Creating a "mix tape" was one of the first things that I started to think about when I heard about this game!
I'm a big fan of 80s retro synth music - there are many great artists producing this type of instrumental music that would be ideal for a game such as this. I would recommend the work of College, who is one of the pioneers of the genre, but also has a very minimalist sound, very well suited to a background sound track or ambience. You may remember his track "A Real Hero" from the movie "Drive"?
The guys who composed the Stranger Things sound track also release similar music under the name S U R V I V E that is worth checking out.
Also the UK duo Futurecop released a few EPs and albums that were heavily inspired by 80s cartoons and fantasy films.