Optical Illusions is a game made by Jeremy Winterrowd in 2006. It shows you some pictures and asks you questions, like "How many faces do you see?". After about five illusions, Sarah, from the film Exorcist: The Beginning, appears, punches the screen and screams, before cutting to a still image of her. The same animation is used in other games made by Winterrowd, like Find It, Hit the Dot and Bubble Wrap Maniac. (In the latter two, the animation ends with the image of Regan MacNeil instead.)
NOTE: The following game contains a screamer.