Unknot is a hyper-casual video game in which players are presented with convoluted drawings of the unknot (i.e. the trivial knot or plane circle) which they must undo with as few moves as possible. The game serves a serious purpose as a research tool for investigating the visual presentation of mathematical knots, by correlating player performance with knot drawing metrics to identify practical guidelines for the effective presentation of knots. This work involved devising a new approach for generating and smoothing knot diagrams at interactive speeds, and implementing two special knot moves aimed to be intuitive for players. Cognitive Load Theory (CLT) informs both the design of the game and the drawing of the knots, to minimise factors that might otherwise mask the effects being investigated.