Pokémon Go is a mobile game which forces player to go outside and take a walk around. In order to catch Pokémons one has to wander miles and miles. Not bad idea at all!
Pokémon Go is available for Android and iOS in the US, New Zealand and Australia (at the moment). However it's possible to install an APK-package on Android. Read on.
Download Pokémon GO APK-package with your Android phone here: http://www.apkmirror.com/apk/niantic-inc/pokemon-go/pokemon-go-0-29-2-release/pokemon-go-0-29-2-android-apk-download/ . If in doubt, wait until Pokémon Go is officially released in your country and grab it via Google's Play Store.
Allow Unknown Sources in Settings -> Security. After that tap the APK-package in order to install it.
That's it! Time to play!
One more thing! You need a proper 4G connection if you want to play Pokémon Go. In addition make sure GPS in on. When all is set, off you go!
Edit: watch out! Backdoored version of Pokémon Go APK-package found! https://www.proofpoint.com/us/threat-insight/post/droidjack-uses-side-load-backdoored-pokemon-go-android-app