Gorilla

Drag the light. Catch every dot that blinks.

Inside the light the field is sharp, and everywhere else it is a blur. Now and then a dot far from the light blinks warm, and you have a second to put the light on it. Three misses end the run.

Nothing gets harder. The dots come at the same rate and wait the same time in the first minute as in the tenth. What decays is you.

Every half minute a dim gorilla walks across the blur. It is never a threat and it asks for nothing, and looking at it costs a dot. The card shows where your light went, and where the gorilla did, and whether the two ever met.

Canvas2D, so the game is whole on any phone. No camera, no account, and nothing leaves the machine.