So yes, it's just Tetris, but it's supplemented thoughtfully. The mechanics beneath the fundamentals are a little arcane, though I personally find that thrilling as specifics are slowly picked apart. The basics are easy enough - clear lines to send trash another players' way - with a few kinks of their own. Clearing a single line won't impact another player, and is more a way of tidying up - to do real damage, you'll have to clear multiple lines at once, with combos and t-spins helping you stack even more punishment up.