I just read a post on Neogaf which explained why after playing Portal 2, Ico felt very tame.
I would like to empathise with the author. After playing Gears of War 3, Tetris really pales in comparison.
On a high level, both games are about using items to eliminate obstacles. One could consider Horde an alternative to Tetris’ levels: as you eliminate more enemies (lines/hordes), it becomes faster and more difficult. In order to deal with this, the game provides you with weapons (blocks/guns).
Now that we’ve established that both games are roughly the same, let’s examine why Gears is the superior game:

