If you've ever played AOE (Age Of Empires) in the past you'll know it was one of the best RTS' of its time and still holds up today as a classic. So when Microsoft announced it was working on a new online version I was excited, but what stood out was that they were giving it away for free.

Free-to-play is fast becoming a popular business model for game developers. Battlefield Heroes and Quake Live were two of the first big titles to adopt it but never saw mass adoption. Now that Valve have thrown their considerable weight behind the it with the popular Team Fortress 2 and rumoured Dota 2, it seems that free-to-play here to stay. But how does it effect the game?

For the first few hours of AOE Online you'd be forgiven for thinking that there wasn't a pay element included in the game at all. The developers have been very careful to hide away anything to do with purchasing until you've grasps the basics of the game. It's only after you've complete the first set of tutorial missions that you're exposed to a purchase upgrade. You're informed that an exclusive item can upgrade your units giving them stat bonuses but at a price, 1840 gamer points in fact, which works out at £15.76. For your money you gain access to the 'premium content pack' allowing you to use rare items, star tech and advisers. Helpfully the AOE website provides a comparison table that makes it easy to see what you get for your money.

The good news it you can pretty much ignore the purchase side of the game if you wish. Casual gamers will have fun with the missions and can play with friends in co-op mode. It's only when you want to get serious with the game do you need to upgrade, and at around £16 that's a lot less than a full retail game.

So far it looks like Microsoft have gotten the balance right with AOE Online. Upgrade purchases aside, AOE Online looks great, is fun and doesn't cost you anything to play. Its hard to complain about that.