Is this possible to make custom race look and music?

Hi, i'm new here, i get this game from humble bundle.

I really liked the game. and i was fascinated of the ability to create custom civilization! ( In Stellaris you could create them... but A.I couldn't play as them! )

Well... i was pretty curious about creating civilizations... and i get an question, is this possible to make custom musics and race looks for civilizations?

I'm very thankful for every reply!