About Green Light
Green Light is what psychologists call a go/no-go task, turned into a game. Shapes flash up one at a time. Most are green circles, which you must tap. Some are red squares, which you must not. It tests two things at once: how quickly you can act, and how well you can stop yourself.
How it works
A green circle has to be tapped before it disappears. Do that and you score a point. Miss it and you lose a life.
A red square has to be left alone. If you hold back until it goes, you score a point. If you tap it, you lose a life.
You have three lives. Roughly two shapes in three are green, which is deliberate. Tapping becomes a habit, and then a red square appears.
Each shape stays for just under a second at first. As your score rises, they vanish sooner, until you have less than half a second to decide.
Playing it well
Decide on the shape, not the movement. The urge is to tap the moment anything appears. Train yourself to see what it is first. Circle or square is as good a cue as green or red.
Accept being a little slower. Early on there is plenty of time. Use it. Speed comes by itself as the game tightens.
Keep your finger hovering in the middle. Shapes appear in different places, though you can tap anywhere to respond, so there is no need to chase them.
After a mistake, slow down for the next one. Errors tend to come in pairs.
Notice how you feel after a run of greens. That is exactly when a red is most dangerous.
Forty points takes real self-control. Among reaction HTML5 games, this one is as much about not tapping as tapping.