While the recent spawning of new content from Portal had set the rumor-mills buzzing about the game’s sequel in-the-making, a teaser for the forthcoming print issue of Game Informer magazine has somewhat substantiated the speculations that Valve’s ‘Portal 2’ is currently being developed.

Game Informer’s Portal 2 page indicates that the sequel is essentially designed as a “stand-alone, full-price retail release;” thanks to the immense popularity of the small-scale-release original first-person puzzler, which has encouraged Valve to devote significantly more resources for the sequel’s release.

The cover tag of the Game Informer, which is projecting an October 26 launch of Portal 2, states: “Aperture Science returns for the people who are still alive,” with an extended ending mentioning a “party escort submission position.”

The overt presumptions that can be made about the forthcoming Portal 2, as inferred from the Game Informer page, include those about the game being a co-op campaign, with “two new player characters.”

In addition, the two sides of Game Informer’s cover indicate that the sequel will largely combine the placidly disturbing test areas Aperture Science laboratory, along with including more overrun areas.

With the Portal aficionados prepared for all the mysteries that Portal 2 would unveil; the sequel, by itself, has a tough task up it sleeve – especially as the original eventually receive as many as “70 industry achievement awards.”