The final concepts for each of the Doctors
Deep inside the Googleplex, just past the giant spaceship suspended from the ceiling, there is a unique office stuffed with toys, art and dogs - the home of Google's famous Doodles.
How Google draws its doodles
How a Dalek moves in the game
London is the backdrop for the game
They have taken the internet by storm, becoming a global phenomenon seen by everyone who visits Google’s homepage.
Google Doodles, which began life as a way for the firm’s founders to tell people they were at Burning Man, have grown into a huge operation.
Recently the team finished its biggest ever challenge - a complete game based on Doctor Who, to tie in with the show’s 50th anniversary.
Stuff was given exclusive access to the Doodle team, led by Londoner Matt Cruickshank, to find out how they did it - and why the Doodle has become a key part of Google’s culture.
The team of 15 is housed in a corner of the Googleplex, and it a unique office where almost every surface is covered with toys and artwork, while the teams three dogs keep a close eye on proceedings (at Google, the dogs are even allowed ID badges).
The Doctor Who project was shrouded in secrecy, with most Google employees unaware it was being created.
It features all 11 doctors, who players must guide round a series of levels, avoiding Daleks and other baddies from the hit show - with levels set in London.
The idea was first suggested by a Google employee to the Doodle team, who say they welcome ideas from anyone.
Normal Doodles will take around six weeks to complete, but Doctor Who took four months to finish, and is the most advanced Google has ever attempted.
Cruickshank first drew the characters on screen, then programmers began building the game, which remained on the Google homepage around the world for 48 hours.
“We wanted something for fans and a game people who don’t know who Doctor Who is,” said Cruickshank.
“The age demographic is huge, I’d say 7-70, and what attracted us all was the science fiction.
"We get a lot of funky ideas from sci fi that aren’t too far from what some parts of Google are working on.
"In fact, we’re just testing the driverless Tardis," he joked (at least, we think he was joking).
The team worked with the BBC on the project, with engineers from other parts of Google joining to program the game.