Force Google to ignore splash page & set www.address.com/home as the home page

Hello. I have an odd question. My client made me create a splash page that serves as a portal to their 2 websites. When you visit the site, it gives you the choice to view site A or site B. My issue is now that this is live, Google sees this splash page as the home page and it has ruined my SEO.
Is there a way to bypass and set as the home page for Google SEO purposes? I have recently set the robots.txt file to ignore the splash page, but I'm not sure this will do what I want it to.
Anyone…
Force Google to ignore splash page & set www.address.com/home as the home page

See original post by telkins