Mind Games Pro

This app includes 19 different games, covering a wide area of subjects, such as math, trivia, vocabulary, and memory skills. It keeps track of your scores and progress over time, as many of these apps do, but it also lets you know where you stand on a worldwide scale by giving you a percentile ranking (letting you know what percent of players scored below you) and standardized score (like what you'd get from an IQ test). [$5; AndroidiOSWindows]