[e2021]

I don't get it, it's just a tweet with ascii art for GoL?

[beaconstudios]

The tweet contains the first phase of a 2-periodic oscillator. It links to a tweet of the second phase, which links back to the first tweet.

It's 2 mutually recursive tweets.

[tape_measure]

The difficulty is linking two tweets to each other. You don't know the url of a tweet when posting, but there are patterns in how the ID is assigned and it's possible to tweet likely guesses until you have success.