It's actually a top-down shooter. 20 small missions, where you do normal sorts of FPS missions, but from a top-down perspective. It looks similar, but honestly is completely different.
After playing it for an hour or two, I'm not having a great time. It's not bad, but it's not good either. I got really excited about buying weapons for campaign loadouts, only to find out that the weapons you buy only last one mission. And that it takes about 10 missions to save up for one. And that the only weapon you can buy without a micro-transaction is the sniper rifle. All in all it's pretty bullshit.
Story's bland - nothing happens. Military talk here, kill some "VIP" enemies that look just like the rest, kill these dudes, military talk, military talk, escort these guys, kill those guys and your name is Spartan Whatever, Hero of Whichever War I Don't Care About Any More.
Gameplay's solid...ish. For the most part you're forced to either dodge bullets or shoot and take bullets. Which is pretty frustrating since your movement speed is halved whenever you fire a gun. But it's okay, because a bullet takes out as little as about 5% of your shields. So who cares, really?
For $6.99, you get what you pay for. And then a little less. But I guess we can't complain since it's a game they didn't have to, and maybe even shouldn't have, ever made. Windows 8 caaaashcoowwww.