Valve swiftly added portals back into the game series called Portal, though they resisted adding Chell back as she wasn’t much of a character and had already escaped. He said: “It was a lot of things, but it wasn’t Portal 2.” Though some elements of that version of Portal 2 still exist, with GLaDOS’ replacement Cave Johnson appearing heavily in the final game, writer Chet Faliszek pointed out at GDC 2012 that this wasn’t what people wanted in a sequel.

To see this content please enable targeting cookies. The game was initially going to be set in the mid-’80s and based around a mechanic called “F-Stop”, which involved using a camera to grab sections of the game’s scenery to solve puzzles. Valve’s initial experiments into a Portal follow-up jettisoned everything but Aperture Science. Portal 2 originally didn’t have any Portals in it

10 is a nice age to celebrate, and it’s also the perfect number of random facts to pluck from the history of one of Valve’s most celebrated games.

I’d like to think that the ultimate goal of Portal 2 was to get me to write an article about its tenth anniversary, so my ego wouldn’t let it go by.