Today's Google Doodle (or Whodle) commemorates the 50th anniversary of the hit BBC science fiction show "Doctor Who", which aired for the first time on November 23, 1963.
The Doctor is an alien (Time Lord) with two hearts from the planet Gallifrey who travels through time and space in his TARDIS (Time And Relative Dimension In Space) and developed an affinity for planet Earth and its inhabitants.
When the first actor to play the role, William Hartnell, began to have health issues it was decided that Time Lords should have the power to change their form, and thus a new actor, Patrick Troughton, took over the role. Since then there have been nine further canonical regenerations on television (note for nitpickers: this doesn't count John Hurt's War Doctor or the 10.5 Doctor) for a total of 11 incarnations.
The premise of this interactive doodle is that the Doctor's mortal enemy, the evil Daleks have stolen the Google logo, and it's up to the Doctor, all 11 of him, to Save The Day.
After selecting your favorite Doctor (don't worry, if you die you'll regenerate into another incarnation), you find yourself in an industrial setting, possibly on the Dalek's home world of Skaro, or more likely in a disused factory in Cardiff, Wales. You move your Doctor either through mouse clicks on the square you want to go to, or more slowly using the cursor keys.
You'll find that obstacles block your way on every level, so armed only with your trusty sonic screwdriver (remember you can't sonic wood) you need to head to any levers you can, and avoid being "EXTERMINATED". Once you've recovered the G you need to head back to your TARDIS and travel to the next adventure.
Next you arrive in prehistoric times. Here you need to navigate your doctor over moving bits of land, avoiding the Daleks, and recover the first O from the Pteradon nest, which conveniently has a ladder on the tree trunk. Heading back to the TARDIS, it's time to go to the next adventure.
Arriving in modern day London, the Doctor has to lower Tower Bridge, then raise it again and call the barge the TARDIS is on, all while avoiding the Cybermen (although they do actually look more like the result of an ill-fated union between a Cyberman and a Quark) and flipping more switches.
The penultimate adventure for our heroic Time Lord takes place in a rainy graveyard with the return of the Daleks (just when you think they've been beaten, up they pop again like the galactic cockroaches they are).
Grabbing the L here opens a doorway through which a Weeping Angel appears. As any self-respecting fan knows, a weeping angel can't move when you're looking at it, but when you're not, if you let it touch you, you'll be sent back in time (or for this game you'll turn to dust and quickly regenerate into another incarnation of the Doctor).
Finally, you have to find the L and the E, which the Daleks have fiendishly left lying around in a seemingly empty laboratory. A moving, electrified power grid in the floor provides the challenge on this level.
Hitting the first switch releases the L and powers up an entire line of tiles preventing your escape. Collecting the L removes the other line you can't cross, but also increases the number of tiles lighting up. The second switch removes the barrier to returning to the TARDIS and also reveals the location of the E.
Once you're back in your TARDIS it's time to travel to the Googleplex and return the letters to a grateful Matt Cutts (not pictured) while celebrating with the other 10 Doctors (although part of that celebration could be that they really toned down the representation of the 6th Doctor's coat).
The "Doctor Who" game first went live on several international Google sites, including Google UK, Australia, and New Zealand. (Update: The Doodle became available globally on all Google sites on Nov. 23.) You can also check it out on its permanent Doodle page.
"The Doctor Who doodle started life as a request from a huge fan at Google," Google explained. "It seemed daunting- 11 Doctor's, 50 years of adventures, countless enemies and time travel! But we loved the idea of science fiction, technology and fun coming together, so we set about creating a multiple level game. … We thank the BBC for trusting us and also helping us whenever needed."
This isn't the first time Google has celebrated the Doctor, in August they added the interior of the TARDIS to Google Maps, and in July YouTube ran Geek Week, which celebrated "Doctor Who" on the Monday. We've even talked about lessons that Doctor Who can teach search marketers here on Search Engine Watch.
Now it's time for you to go and #SaveTheDay.