Starting at the Rathaus, Zurich's riverside town hall, you'll open the Explorial app, enter the 6-digit game code that you received by text and Viator chat message, and set off along the Limmat. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. The Grossmünster looms first — legend says Charlemagne's horse knelt on this spot, and Zwingli later preached the Reformation from its pulpit. Riddles handle both stories. At Sechseläutenplatz, trivia explains the Böögg: the exploding snowman whose burning head forecasts the Swiss summer, more trusted than any meteorologist. Then Paradeplatz closes the route, the tram-crossed square where Switzerland's banking giants keep their headquarters and their secrets. Around two hours along both banks. The leaderboard settles the score — in Swiss francs of glory only.