Rumours of Portal 2 have been floating around ever since Portal lead, Kim Swift, made a sideways mention of it back in February, right at the end of this interview. Now that dust is stirred up once again with the Kotaku-spotted job advert, asking for a voice actor to play Aperture Science's late boss, Cave Johnson.
The ad, on the subs-only Breakdown Express, contains a pretty detailed biog of the self-made billionaire, stressing that applicants will need good comic timing and dramatic skill for the role. It's below the jump for those wishing to avoid spoilerific fun.
Picture nabbed from Kotaku.
So there's much to chew over. Featuring a dead character doesn't necessarily suggest prequel, but it of course makes it an option. It could equally be archived recordings. The most intriguing line would have to be, "Goes from sidekick to principle antagonist."
However, reasons to be suspicious: The first I would say is the spelling error in the job advert. That doesn't seem very Valve. "Sarts to lose his grip on his humanity..." The second is that Portal Queen Kim Swift is currently working on Left 4 Dead, and it would seem very odd for a Portal sequel to be in development without her. Although they may simply be planning ahead.
Is it for real? We've asked Valve and are awaiting their response.