Halo: Spartan Assault, the top-down shooter spin-off of Microsoft's popular sci-fi series, is available to download now on Windows 8 and Windows Phone 8.

The game costs £4.99. Windows 8 users can grab it from the Microsoft Store on their Start menu.

Co-developed by 343 Industries and Vanguard Games, Spartan Assault follows Spartan Commander Sarah Palmer across 25 missions set between the events of Halo 3 and Halo 4.

Steve went hands-on with the game last month and compared it to a Smash TV-like sci-fi shooter.

A release on other platforms has yet to be announced.

Source: Microsoft Store