While E.T. isn't the most fun game for the Atari 2600, it is actually far from the worst. If you read the instructions, the game made a lot more sense and getting out of the pits wasn't that hard. it is likely that because of the Alamogordo legend that E.T. got it's reputation as the worst game ever. but it's all exaggerations.

Angry Birds was never fun. It was only popular because it came pre-installed (and not removable) on millions of smart phones and was free to others. It was (and still is) advertised everywhere you go.