Well, yeah, Tetris is a game. But it's a game in the same way that a termite is also a living species just like an elephant is another one. They just do not benchmark on the same scale.

I strongly disagree. A game should be first and foremost measured by its gameplay, and Tetris easily beats 99% of the games released each year on that department.

I wouldn't picture myself playing Tetris all my life, just like tons of games in the same time that you find nowadays on mobile phones, so I strongly disagree with your view. I wouldn't count Flappy Bird as a "game" as well - for me it all goes in the same bucket as Tetris, i.e. something to kill the time, but nothing I would consider to be a serious game in any measure.