Below is a video clip of FunctionHero gameplay showing an early level and an advanced level.
A piece-wise function scrolls across the screen from right to left. Your task is to classify the behavior exhibited by the function at the point where it intersects the vertical blue line which is the target line.
Play continues until the time expires. At any time, you can swipe up from the bottom to open the in-game menu and pause the game.
In the first few levels, help mode is turned on to help you learn about function behavior. In this mode, intervals of the function and critical points are color coded to match the color of the button that identifies the correct behavior. In later levels, each function piece is a single color and you have to identify the behavior.
Increasing, decreasing, and constant behaviors occur over intervals of the function domain and therefore should be held the entire time the behavior occurs. Maximums, minimums, and inflection points are critical points. Therefore, they occur at a single point and should be tapped as the corresponding critical point crosses the blue line.