Google is well known for throwing easter eggs in to its software, particularly with Android versions. For the past two years, there's been a hidden Flappy Bird-style game which you access by heading in to Settings > About Phone then tapping multiple times on the Android version, then tapping repeatedly and long-pressing the Android version logo.
Having changed with Android Nougat to become more complicated, Google returned to more simple roots with Android Oreo.
This year's Easter egg is a simple octopus on screen that you drag around and manipulate. Here's how to get it...
Android O "Oreo" easter egg
Your first step, as already mentioned head to the settings menu, scroll all the way down until you reach "About Phone", tap that and find "Android version". If you press this option multiple times repeatedly, you'll get to a screen showing the Android O logo on your wallpaper.
Repeatedly tap the "O" a few times then press and hold on it and you now you should see a black octopus onscreen. You can now drag the octopus around the screen, pick it up, drop it, mess around with it.
Android N "Nougat" easter egg
You can get to the Nougat easter egg in much the same as as Oreo, but the actual game is much more involved. Activate the easter as normal by going into your Settings > About Phone > Android version. Repeatedly tap on the Android Version tab until the "N" appears on screen.
Swipe down from the top of the screen to reveal your quick settings toggles and hit "edit". You should now see a cat face icon with the label, "???? Android Easter egg". Drag and drop this icon to to the main quick settings options and place it where you want it. Now, the fun can begin.
Hit your home button and then drag down the quick settings shade from the top of the screen again. This time you should see an "empty plate" option. Tap it and you'll see an overlay with four food choices: Bits, Fish, Chicken and Treat. Select one, then continue using your phone as normal, and wait.
Eventually, you'll get a notification telling you that a cat has snagged one of the treats. But it doesn't always work, which is kind of the point of the game. You have to keep trying, using different treats to bait a cat.
When it does work, you'll get a notification saying "a cat is here" with the number of the cat listed underneath. Tapping on the notification reveals a new screen with a cat icon which you tap once to rename, or long-press to reveal sharing options. You can save a full resolution version of the cat's picture to your device, or share it to all your social media accounts like every other crazy cat owner.
Android M "Marshmallow"/Android L "Lollipop" easter eggs
Right before Android L was launched, a massive hit game called Flappy Bird hit the world of mobile apps. It was hugely popular, until the developer pulled it. Still, it was around long enough to inspire Google's Android easter eggs.
In these two versions of the Android OS, go to Settings > About Phone, and repeatedly tap on "Android Version" the same as the others. Now repeatedly tap and long-press on the logo that appears. Now, a mini game should load. In the game, the idea is to tap the screen to help your Android Robot avoid getting stuck on lollipops or marshmallows, depending on which version of the operating system you're running.