I play tetris a lot, but when doing so, I don't think about it. Tetris is a game that you can play without actually thinking about it. I play ltris, and if I play another variant that has different colors for different shapes, or some other minor difference, I'm completely screwed. In fact, I play tetris in order to be able to think about something else, it employs my hands and I can clearly think about something I want. The game itself is just a complete routine.
(And by the way, I can play tetris completely in my head, without a computer. Just close eyes and imagine playing it. And it actually feels like playing tetris. Shapes randomly appearing at the top, that I try to place as I would in the real game, then they make rows, disappear, and after some time, it gets so fast that it overwhelms me and I lose :-))