Angry Birds Opera

Angry Birds Opera was a free version of Angry Birds available for PCs using the Opera web browser. The game was available at the following site:opera.angrybirds.com hoewewer Rovio didn't got time to release it so is mostly a planned version of the game

Why it wasn't released to the public
Angry Birds Opera actually was a planned version of Angry Birds howewer Rovio didn't got time to release the website and game but they show a screenshot of the testing website