If you fancy having your mind somewhat blown, try playing the Mass Effect 2 demo in your browser. Unlike most graphically impressive browser games, this isn't a huge download running via a special plugin: all you need is Flash and Java, which you likely already do, and you'll be playing in a few seconds. The only catch is you need a good connection - about 10Mb/s - and the demo won't appear if you don't.

The service is called Gaikai, and it's live in 12 countries right now. The focus is on letting you into the game with no fuss or sign-up process, so it's perfect for demos. At the end of the Mass Effect 2 or Dead Space 2 demos available now, you get a link to buy the full game.

If the Mass Effect 2 demo link doesn't pop up when you visit the Gaikai site , try the Spore one - it has the same requirements but it'll tell you what's wrong if it doesn't work.

The service has actually been running in a low-profile way for a couple of months. There's a slight lag on interactions when playing on our office connection, but performance is generally very good. Since it's web based, it means you can now play these PC games on a Mac or Linux system. It's set to be demonstrated in full at the Games Developer Conference this week.

Unlike the similar game-streaming service, OnLive, Gaikai doesn't charge for its services and allows users to play in their browser right away. At the moment it only offers some choice selections from EA, but is hoping to move onto including a larger catalogue of blockbuster hits from them and other publishers.

Writing on his blog CEO David Perry explains that he hopes to eventually end up with servers in every major city in the world to stream data from, saying that "if [Gaikai's] engineers work really hard, they can maybe squeeze out another thousandth of a second from our compression but if we set up in a data center two states closer to your house, we dramatically improve the performance".

The creator of Earthworm Jim hopes to eventually expand the service to allow YouTube-style embedding of demos on websites, and the service will eventually work with Facebook. The aim is to have the embedded demos appear on Facebook, and at the end of reviews, so players can hop straight in and play.

Other demos currently available include Spore , The Sims 3 and, after completing a short survey, Dead Space 2 .

Let us know if they work on your connection and, if so, how the performance feels to you.