The main appeal of tetr.io for me is it's ranked mode. You need an account, and to play a few games for your elo to stabilize, but multiplayer->tetra league is a great way to 1v1 people around your skill level
Ah, did not realize that .. of course would need an account. Will have to try it out maybe, been loving the Tetris Effect multiplayer games, maybe will try this out too.