I couldn't help but notice your username. I actually own an original ET game cartridge for the Atari 2600. Sadly not from the dump site though, also no box or manual, but I'd almost be willing to bet all the money in my wallet the game still works if I had a working Atari to put the cartridge in.
Oh wait, I have $0 in my wallet, so I guess I'm betting $0 that it works LOL! ๐๐คฃ
I have actually tried the game with the Stella Atari emulator, and yeah, the game makes no fucking sense ๐คฆ
Edit: Is there a PDF or otherwise scanned copy of the manual out there?...
IDK, Merry Christmas ๐