GameCalc is a gamified calculator app. The player start with a limited number of buttons. They unlock new buttons on the calculator by doing math. For example, 1+1 unlocks 2, and also unlocks the multiplication operator (because multiplication is defined as repeated addition).
It was created for HackRice 2014, a hackathon at Rice University, where it won 1st place. GameCalc was a collaboration with Jacob Van Geffen and Daniel Kermany.