A Major Breakthrough

I've been playing Tetris (NES) for several months attempting to get some kind of really high score. I'd accrued about five games between 220 and 230k, finding it basically impossible to go any higher. Then today, somehow, I managed to hit 315,162. Technically, I think one could score maybe 400,000 given all the right pieces before they start falling so fast that you can't even make it all the way to the side before hitting bottom (level 17, I find), and I'm sure the theoretical high is probably close to 600,000, but I might have to stop playing for a while.