Thank you! I'm very grateful I was contacted about putting it on portmaster, and glad you could enjoy it that way.
The game is free because I simply wanted The Rush to be as easily accessible as possible. It is exceptionally unlikely that the first Steam game by an unknown indie dev in a fairly niche genre would see much success or appeal, so I opted to make the game free and sell the soundtrack to maximize exposure. Perhaps that is a pessimistic viewpoint, but I believe it was the right decision in this case.
Thank you for your support