Valve has said it will definitely be making more Portal, confirming plans to add significantly more than just "a bunch of new puzzles".
Speaking to Eurogamer, spokesperson Doug Lombardi said it was less a matter of if and more a matter of what and when.
"There'll be more Portal, for sure. But the details of that, to be honest, we're still working out," he said.
"The only smart thing we did for Portal was to hire those seven kids and give them the support they needed to make the game."
Unsurprisingly Valve is reluctant to be rushed by a release schedule. It's adopting the same policy for Half-Life 2 finale Episode Three.
"Gordon is our number one guy," said Lombardi. "In Episode One I think we left people with some big questions. After Episode Two people saw it was going somewhere.
"With Episode Three we want to live up to the promise of where we are taking things to; there's a lot of work being done to make sure we deliver on that promise."
He added, "Exact details on what's next for Gordon are a way off; probably months not weeks."
The chances it will all fall into another Orange Box are slim. Valve works to its own timetable and, if multiple projects come to a close around the same time, then potentially it could happen.
One thing you can count on is value. Valve wants all of its additional content to be free, for example, and to ensure gamers know a product with its name on the box is worth buying.
Coming up next are maps for Team Fortress 2, which will be bundled into downloadable packs for PS3 and 360 at some point in the future. For free. (Update: Doug has since informed us that the fate of the maps on console remains "TBD" for now. Apologies.)
Oh, and Lombardi is chuffed you lot praised the individual components of The Orange Box enough to put it high on the list of Eurogamer readers' top games of 2007.
"That's awesome," he exclaimed. "Eurogamer is one of our favourite sites [oh stop you big flirt], and it's a testament to the fact you attract intelligent readers that they chose The Orange Box as their favourite game."
Hehe, he called you intelligent.