So an interesting bug...I installed Sin's via Steam and ran no problem. Upon exiting out and relaunching it does not run right. Let me explain:
I open the Rebellion launcher and click to launch Rebellion. I get the splash loading screen with the Rebellion logo. Then I hear the intro movie playing, but the screen is black. I press enter in order to skip the intro movie and then the audio ceases. I noticed after alt-tabbing a bunch that I will eventually get the main menu to pop up. When I attempt to interact with the menu the screen goes black again. This issue is persistent.