The much anticipated Halo: Spartan Assault is now available from the Windows Phone Store, arriving as a high profile exclusive for Microsoft's mobile platform. The top-down shooter, which features cutting edge graphics and best-in-class audio, is set in the Halo Universe and includes many familiar elements from the console title, including the signature immersive story line, characters, and weapons.

Microsoft has gone to a lot of trouble to create a "pick up and play" title with intuitive controls and the ability to cloud save game status across multiple devices (allowing you to start playing on Windows Phone and finish playing on a Windows 8 tablet).

As we previously described, Halo has a long history and is one of Microsoft's key gaming brands:

The game is described as exploring the "first missions of the Spartan Ops program" and diving "deeper into the back story of Human-Covenant wars". Across 25 missions players will "see" though the eyes of either Commander Sarah Palmer or Spartan Davis, who are stationed aboard the UNSC Infinity.

Halo is one of Microsoft's biggest gaming brands so its arrival on Windows Phone is a significant moment, with the potential to give new users a reason to pick up a Windows Phone device. It will also be promoting Microsoft's multi-screen strategy as it will be possible to pause the game on one device and pick up and continuing playing the game on another. 

Here are the top features of the game, as listed by Microsoft's Halo Waypoint site:

• Original "Halo" gameplay. An action-packed, single-player campaign spanning 25 missions in battles never before experienced in the Halo Universe, all played from a top-down camera view.
     
• New and immersive storyline. An original story set between the events of "Halo 3" and "Halo 4," experience a new war with the Covenant, the first missions of the Spartan Ops program and the rise of Commander Sarah Palmer, all with best-in-class graphics and audio.
     
• Built for simplicity. A unique fusion of touch and console like controls for easy pick-up-and-play gaming, with the added flexibility of keyboard and mouse controls on Windows 8 PCs and tablets.
     
• Integration with "Halo 4." Earn experience points (XP), all-new Achievements, and unlock emblems for your "Halo 4" Spartan career, with additional integration features available after launch. 
     
• Nonstop competitive fun. Compete against friends in Leaderboards or hone your skills against an onslaught of Weekly Challenges while collecting more than 40 in-game Achievements and Medals.
     
• In-app purchases. Grind to earn upgrades or speed up your training by purchasing credits for boosts, unique weapons or armor abilities.  
   
• Only on Windows. Available only on Windows 8 PCs and tablets and Windows Phone 8 devices. 

Windows Phone Store description:

Halo: Spartan Assault brings the excitement of Halo combat to touch-based devices for the very first time. Battle your way through 25 action-packed missions against the Covenant as you explore the origin of the Spartan Ops program and Halo 4's Spartan Commander, Sarah Palmer.

It's time to join the assault, Spartan!

Halo: Spartan Assault can be downloaded from the Windows Phone Store. Unusually for an Xbox Live title there is no free trial. The game costs £5.49 / $6.99. There are some geographical restrictions on the game's availability, so it may not be available in your market. In the US Verizon has a 30 day exclusive.

The game is a 691MB download and therefore will require about 1.2GB of free space on your device to be successfully installed and must be downloaded over WiFi. Currently the game is only available for high specification (1GB device), but an update is due later in the summer that should ensure compatibility with lower specification devices (HTC 8S, Lumia 520, 620, and 720).

The Windows 8 version of the game is also available from today from the Windows Store. Do note that the Windows 8 version will require an additional purchase to the Windows Phone version.