Geometry as algorithms: cross products and orientation, the shoelace area, point-in-polygon, segment intersection, convex hulls, closest pair, sweep line, and Voronoi diagrams.
Free to start · adaptive placement finds your level · reviews timed to your own forgetting.
Every idea is taught with motivation and a worked example before the drills, and an FSRS spaced-repetition engine schedules each review for the day its model predicts you would forget it. A short placement check finds what you already know, so you start Computational Geometry exactly where it's useful.