First off ET is NOT or ever will be the worst game or even a bad design for a Atari 2600 game.
It was the most popular game during the 80's videogame market crash.
It had more screens than most the game, brain dead simple mechanics and a step by step instruction on how to play and win the game in it's book.
The shovelware a year to up to ET's release caused the crash, not the game itself.
Also it was the last game where retailers would "take back" a video game and refund full money breaking another nasty 80's habit of buy game, take home play for a day or two, see all there is to see, bring back and complain didn't work, repeat.
The so called worst games are basiclly sheep Bahhhhing at one guys opinion and cut and pasting to their own website. Most who claim 2600 games to be bad never even grew up in the 2600 days and knew what the heck to even base them off of.
You want a real example?
2600 Strawberry short cake mix and max
River rafter
Any of the sword quest games (only playable with a comic book)
Chase the chuck wagon.
NES Total recall is a very good all in one package of what is BAD in games.