Reaktions is a free and highly addictive game of speed and intelligence.
A simple test of your reactions. In Classic mode, touch the square before it disappears, the further you progress, the less time the square shows.
In Advanced mode, not only do you need to use your fast reactions, you need to remember which shapes give you points, which deduct points and which ones end your game straight away. Again, the further you progress the less time you get to react.
Whether you play in Classic mode or Advanced mode, you will need to show great speed and memory to build up your score.