Games that ask the player to do nothing more than wait while numbers increase have seen a surge in popularity. They fill a developing modern need for activity, giving players a window in their browser they can compulsively check while cycling between other interests. The fact that they ask for so little makes it easier for them to fulfill a multitasking impulse, scratching the player's itch to feel like they're accomplishing many tasks when their main focus (like listening to a lecture or working at their desk) requires them to sit still.