You alternate pressing the left and right arrows keys to move the River Man forward (you want to mashing them to increase your score). To score on a soul, you have to have your guy be above them and also have the key match their type. You can swap type, by pressing the left key followed by the left key or the right key follow by the right key (it depends if you are collecting a good or bad soul). By doing all this, you score points and the final score is calculated after 60 seconds.