I'm a geoscience student and built this over the past few weeks as a side project. It's a daily geography puzzle where you guess the mystery world capital in 6 tries. Each guess returns: distance in km (Haversine formula), compass bearing (spherical trig), and attribute matches for continent, hemisphere, coastal status and population range. Same capital for all players worldwide each day — picked deterministically by hashing the date against the capitals array, no server or database needed. The share card was fun to build — instead of just copying text to clipboard it renders a boarding pass image on the client using the Canvas API, then uses the native Web Share API to attach the image directly to WhatsApp/iMessage. The departure city is your first guess, destination is always "???" so no spoilers. Stack: Next.js 14, TypeScript, Tailwind, react-simple-maps, canvas-confetti. Deployed on Vercel free tier. https://capitalle.app Happy to go into detail on any of the technical decisions.