Vanguard Games and 343 Industries are launching a Windows 8 and Windows Phone 8 version of Halo on Thursday. The top-down arcade shooter, Halo: Spartan Assault, is available in the Windows Store and Windows Phone Store priced at $6.99. As Microsoft's Windows stores aren't combined, there's no universal application so you'll have to pay separately for each version if you want to play them across a Windows PC, tablet, or notebook and a Windows Phone. Unfortunately, Spartan Assault is limited to Verizon Windows Phone customers until August 16th, and you'll also need a device with 1GB of RAM as 512MB handsets aren't supported just yet.

Nevertheless, this is fully touch-enabled version of Halo. Although the the Halo franchise is known as a first-person shooter, Spartan Assault attempts to blend touch and Halo together. I got a chance to try out an early version on Windows Phone 8, and while it certainly looks like a mini version of Halo, the controls can be a little awkward on a touch screen. Shooters are incredibly hard to do well with touch, but on Spartan Assault you have a circular area on the left-hand side that controls movement, and an identical area on the right-hand side lets you aim and fire weapons, pick up and use items, and get in and out of vehicles. While I was unable to test the Windows 8 version, I found it hard to aim with the Windows Phone version. There's a slight swipe gesture you have to trigger at the same time as aiming. It's not ideal because running while shooting gets complicated, but there's a soft lock auto-aim so you get used to it.

If you're a Halo fan then the layout and top-down action will remind you of Halo Wars. This is obviously a shooter, and not a real-time strategy, but I kept being reminded of Halo Wars as I ran around blasting Grunts. Aside from the gameplay, Spartan Assault is set between the events of Halo 3 and Halo 4, with a focus on the backstory of Human-Covenant wars. You can play as either Command Sarah Palmer or Spartan Davis as you shoot your way through various Covenant enemies. Along the way there are ways to upgrade your weapons and enable performance boosters by using in-app purchases for credits.

Although it's mainly designed for touch, the Windows 8 version works with a keyboard and mouse so you're not forced to use a touchscreen tablet or notebook there. As this is an Xbox Live game on Windows 8 and Windows Phone 8, you'll earn achievements throughout the game that add to your overall gamer score. More interesting still, if you play the game on both phone and PC, your state will sync between the two devices. There are some unlockable items for Halo 4 as well, with emblems, XP, and new achievements available.

The real story here is that this is launching exclusively on Windows 8 and Windows Phone 8 as Microsoft continues to push its mobile and tablet platforms. I can't help but feel that a game like this should have arrived when the Surface launched in October, but it's encouraging to see it finally available. The only downside is that if you're living in a Microsoft ecosystem then you're going to have to pay out $6.99 twice to play it across your tablet and phone. Microsoft continues to push a more common experience and app platform between Windows 8 and Windows Phone 8 — and the game sync is evidence of that — but Halo Spartan Assault is a reminder of just how separated Windows is, for now.

Update, August 17th, 2013: As expected, Verizon Wireless' exclusivity on the title has ended — all Windows Phone 8 users with a device that has 1GB of RAM can download the game now.