Well, a whole load of information about Portal 2 leaked... the entire Game Informer article was scanned and posted online. I am super hyped about this game now.
***************SPOILER INFORMATION BELOW!!!!*************
It takes place 100 years after the original portal, so it will not likely tie directly into the Half-Life storyline. Chell is returned to the lab in the new ending of the first game, and placed inside a cryo-chamber thingy. In the end of the original game, all those orbs that light up around the cake are personality cores that can function on their own. One of them wakes you up, and serves as a guide around the somewhat ruined labratories. As if it wasn't obvious from the song, GLaDoS is back as well. There are many new physics features being added, such as liquids that can coat surfaces to give them new properties, suction tubes, projected bridges that can go through portals, spring boards, lasers and reflector cubes, weighted spheres, and more.
Also, the Co-op is going to be its own full length campaign. Both players take control of robots. One is made from a personality core, the other is made from a turret. Sadly, neither of them speak. Both are equipped with a fully functional portal gun, so you can have a total of four portals out at once.
Finally, the article confirms that Valve is porting all their games, along with Steam, over to Macs.
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