Good news though is that if you already own it for Windows 8 or WP8 it will only cost you $4.99. Game also comes with extra levels and online co-op. Xbox 360 version coming in January. Hopefully WP8 will get the new mission and co-op play.
Source: 'Halo: Spartan Assault' for Xbox One launches on December 24th for $14.99 | The Verge
Source: 'Halo: Spartan Assault' for Xbox One launches on December 24th for $14.99 | The Verge