Mechanicus and
Ixion
Both games came out fairly recent and have OSTs by Guillaume David. They are both good games on their own, but get great due to the OST.
You can check tehm out here:
https://www.youtube.com/watch?v=ZLsX9WUdYnU&list=PLnSG0OA5vYnTLQ77f5EmLoW52vIX5jAAK https://www.youtube.com/watch?v=RhTXyUERugQ&list=PLLIWYDpOq7WJYefSkcfYujE5JaLmB0Ezf
Huh, I haven't thought of that.
Openly and well communicated, that could be a good monetization scheme for this kind of software.