Xylem: The Code of Plants

This paper describes the impetus behind and design of a quasi-casual math puzzle game with the goal of crowdsourcing formal software verification through the analysis of loop invariants. This game, Xylem: The Code of Plants, presents players with puzzles derived from data produced by loops in a particular piece of software. Solving these puzzles involves finding and expressing a loop invariant that holds for that set of data, which results in an annotation in the original code. In this way, players can contribute to the effort to formally verify a piece of software while enjoying mathematical puzzles.