Yes, we know it's an old game, but that doesn't mean it's not still fun. Some things over 5 years old are still fun you know...
You play the game in a new window which will open miraculously when you click 'Start Tetris' below.
First, press 'L' to choose level (keep pressing it to change level).
Press 'S' to Start and, when the shapes start falling, move them left with the '4' key and right with '6'. Rotate them (anti-clockwise) with '5', and press '2' to hurry them on down. You may find it easier to use the numbers on the number pad on the right hand side of your keyboard (they have arrows, too).
You get points for filling complete lines.
You can see in advance what shape is coming up next in the box at top right, and prepare your strategy.