Seven columns, six rows, and pieces that fall to the lowest free slot. You pick a column, not a square, which is the entire design: the move you want is frequently one row above the move you are allowed, and setting it up means giving your opponent the square underneath it first.
Play against the machine or hand the screen to somebody next to you. There is a share link if the person is not next to you. Games run three or four minutes, and the tenth one is when you notice that the second player has a defence and the first player has a forced win, and that neither of you has been finding either.