Firstly a massive thank you for the kind words, it really means a lot to us as a small studio of beginners, and we're so excited our game is getting seen by so many people :D
Both the theme song and the final score are original pieces we had composed for the game by two very talented musicians, and they're not currently available to download anywhere. We're getting a lot of requests for them at the moment though so keep an eye out as they may become available :) You can follow us on @captiveaudienc3 for updates etc!
If you want to check the composers other work out though it's Mathew J Rees who composed the final score for us, and Jo Henley of Beanie Studios who wrote the main theme!
Thanks again for the kind words, and we're really glad you enjoyed the experience.
Edit: Here are some links to their work for you.
Jo Henley: https://soundcloud.com/Beaniestudios
Mathew Rees: https://www.mathewjreescomposer.com/