I often mock game stories, because they are so mockable: generally totally irrelevant to gameplay, and often egregiously badly written, full of thud and blunder, signifying nothing. The story in These Robot Hearts is, objectively, irrelevant to gameplay; yet it is curiously affecting, a science fictional story of love and loss, carried in thirty-one lines between each of thirty-one levels. It's a little bit of narrative triumph, really, a succinct little poem.
The game itself does not suck either; positioned in the screen are a number of gears, with hearts about them. Clicking a gear rotates it 90 degrees. A heart positioned between two gears is carried by whichever rotates first. The objective is simply to bring all hearts to an upright position, at which point they turn red, and the level completes.
It's a simple dynamic, and I'm not sure it would carry a longer game, but there's enough variation to carry this one, and while, as with Rubik's Cube, what you need to accomplish is clear, and the essential algorithm for solving can be deduced reasonably easily, the difficulty ramps up nicely.