Impressions: Valve's Weier details Portal 2 co-op at PAX Prime

Portal 2 was shown to the public for the first time at PAX Prime last weekend, and while no one got hands-on time, Valve's Josh Weier was there to show us a bit of the puzzler's co-op portion.

First and foremost, those who felt the first Portal was a bit light lengthwise will be pleased to know both the single-player and co-op modes are twice as long as the original game. Also, those who felt tinges of motion sickness or vertigo with the first one shouldn't be troubled this time out; the field of view has been changed.

The co-op portion of the game's story is independent from the single-player. Obviously, you and your partner will have to work together in order to complete each stage.

Valve has included the ability for you or your partner to throw up an hint icon on the screen, which designates where you'd like the other player to open a portal. You're using the same gun you had in the first game.

Hug it up

These hints are extremely useful, especially as the two players aren't allowed to speak to each other. It's just hints and emotes for communication.

Emotes can be used to hug it out with their partner, wave, or complete other small gestures.

The hint system was demonstrated to the audience in a situation with a light bridge. In order to use the bridge to get into the next room, the players had to use the portal guns to make the bridge extend. A player would throw a hint up on a wall, the partner would open a portal there, and the first player would throw its portal up and walk through to the other side.

Another instance of required cooperation where hints were useful was a room with lasers, which are new to the series. In this room, one player would insert a reflecting cube into the laser's path, while the other player opened a portal in the wall for the laser to be reflected through. Each player would then open portals in the walls deterring the laser's path until until it was no longer restricted.

Lasers will play a significant part in some of the game's puzzles, as you'll sometimes have to use reflector cubes to aim lasers at turrets in order to destroy them.

"Chasm filled with deadly liquid"

At one point in the demo, Valve showed a room obstacled by a large chasm. In order to get to the other side, a portal needed to be opened allowing one of the players to build up enough momentum to shoot across the chasm.

One player opens two portals, which allows the co-op partner to keep slipping through them, gaining speed constantly. Once the player gained enough momentum, the player's partner shoots a portal into the wall on the other side, and the player came flying out onto a platform.

Should your partner not open the portal in the correct spot, you'll fall into the chasm filled with deadly liquid. Tough break. However, you appear back where you first started in the room, so it's not like you'll have to walk too far to restart.

Once you finally reach the other side of the room, you just repeat what your partner did to get you both across.

Throughout play, Glados's voice twits along, encouraging you or throwing witty barbs your way should she feel you're not doing as well as you should.

All in all, co-op in Portal 2 looks like it will be loads of fun, and with twice the puzzles and length as the first game, it should lock you in for time.

You can check out the demo we saw of Portal 2 through the video we posted for you on Saturday.

Portal 2 releases on February 9 for PC, PS3, and Xbox 360.