Video game fans became giddy last fall upon hearing that Microsoft was developing a Siri competitor for Windows Phone code-named Cortana, after the AI companion of protagonist Master Chief in the Halo series. Now, it looks like Microsoft is going all in on that sci-fi vision for its personal assistant: Jen Taylor, the actress who played Cortana, is onboard to become the voice behind the information service, Microsoft blog MSFTnerd reported Thursday.