Angry Birds

Angry Birds

The amazingly popular iOS game moved to Android a while ago, earning over two million downloads during its first weekend of availability.
The Android version is free, unlike the Apple release, with maker Rovio opting to stick a few adverts on it rather than charge an upfront fee. The result is a massive and very challenging physics puzzler that's incredibly polished and professional. For free. It defies all the laws of modern retail.
Angry Birds for Android was first available to download from app store GetJar but is now available through Google Play.