I'm an old LG user, yet I'm relatively new to its tournaments.

Can someone explain to me how infinity works?

The infinity tournament never ends.  You get a new game every two weeks, and you move up or down the leader board.  It's like a ladder.

The infinity tournament has changed the rules a few times. I think the latest rule is stated in this post :)

Infinity is more than possible

… except at zombo.com