Google takes itself very seriously these days, but that hasn't yet stopped its engineers from creating "easter eggs" -- unexpected features and games which appear when you search for specific terms or hit special keys in other Google products. Here's our complete list.
We've run guides to Google's easter eggs in the past, but an update seems overdue to add new options (and remove ones which no longer work). For this listing, we're looking purely at easter eggs which Google has actually built into the site, rather than "search bomb" results where searching for a particular term produces a surprising result. (Those are fun, but won't necessarily work long-term, given that Google constantly tweaks its search algorithms. The introduction of Google Instant, where search results are predicted as you type, also means people are much less likely to see the 'I'm Feeling Lucky' button anyway.)
Unless we specify otherwise, you activate the easter egg by searching for the suggested term on Google's own site. We've included links where appropriate, but some easter eggs only work as you are typing. Some of the newer easter eggs (which load games or animations) may not work on older browsers.
Search for Zerg Rush and your search results will be transformed into a game where you have to stop the letter 'O' from destroying your search results.
Life, the universe and everything
Google Reader Ninja
Google Reader has adapted the Konami code (a cheat sequence for games) for an interesting hack. While in Reader, type this sequence: up, up, down, down, left, right, left, right, b, a -- and check out the ninja-loaded result.
Search for recursion and Google promptly asks: "Did you mean recursion?" Call me geeky, but this always makes me smile.
Picasa Teddy Bears
Type Control-Shift-Y in Picasa and you'll see teddy bears. Type it again and you'll see more.
Google Earth Flight Simulator
The most detailed easter egg we know. Type Control-Alt-A in Google Earth to access a flight simulator.
Once in a blue moon
Search for once in a blue moon and you probably won't get the result you expect.
Hold down the left arrow key while watching a YouTube video and you'll get to play the classic phone game Snake. (Availability for this can vary depending on the video.)
Type "Do a barrel roll" into Google and the site will itself do a barrel roll. (You do have to be on the Google site for this to work; it won't operate from a link or if you use your browser search bar.)
The loneliest number
Search for the word 'tilt' on your mobile phone, Google will tilt the results screen. Similar effects can be seen with 'tilted' and 'askew'.
Search for anagram and Google will helpfully ask: "did you mean nag a ram?" (Whether you choose to actually nag a ram is up to you, but remember: they have horns.)
Spotted an (official) Google easter egg we've missed? Share it in the comments.