Is this some kind of code, or just ascii art tweets with links that loop?
Latter.
I don't get it, it's just a tweet with ascii art for GoL?
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.
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.