Angry Birds is a port of the famous Android/iOS/Web game Angry Birds for the Sega Genesis. It was originally developed in China by a huge fan of the Angry Birds game and the original ROM is available to download for free. As a result, pirates have put it on cartridge form and sold it to the public. There is also another version on the Famicom (mostly Famiclones).
The game is largely incomplete and contains a bug which makes the game crash after pressing the Reset button.