Berchtold's Secret — The Hidden Passages of Medieval Fribourg
Uncover the conspiracy behind Duke Berchtold IV's three medieval bridges. Decipher coded stones and expose the hidden network that controlled Fribourg's fate.
📱 1 to 10 phones · 1 team per phone · Independent codes
In 1250, Duke Berchtold IV of Zähringen built three covered wooden bridges across the Sarine River in a single year—an unprecedented feat that raised eyebrows across medieval Europe
Berchtold's Secret — The Hidden Passages of Medieval Fribourg
You are a diligent apprentice chronicler, tasked with verifying the official history of Fribourg in the year 1250.
Duke Berchtold IV of Zähringen built three covered wooden
In 1157, Berchtold IV of Zähringen founded Fribourg, a strategic city. Upon his death in 1186, the dynasty ended, leaving behind a growing city and many secrets. An ancient mystery connected to its bridges and ramparts awaits discovery. Follow the founder's footsteps and uncover his hidden legacy, crucial to the city's history.
« Friburgo, quae sita est super Sarinas ripas, munitissima civitas »— Chronique de Saint-Denis, XIIe siècle
Berchtold IV et la fondation de Fribourg
In 1157, Berchtold IV of Zähringen, a powerful duke of the Holy Roman Empire, founded Fribourg on a defensive meander of the Sarine River. This strategic position controlled the trade route between Germany and Italy, a source of considerable wealth. The duke designed a fortified city according to an innovative geometric plan, with perpendicular streets and regular blocks — revolutionary urban planning for the time.
The premature death of Berchtold IV in 1186 interrupted his grand project. His successors completed the fortifications and extended the city westward, creating the Bourg and Hôpital districts. The bridges over the Sarine — Berne Bridge, Middle Bridge, Saint-Jean Bridge — became the keys to Fribourg's prosperity, allowing taxation of all crossings and enriching the city for centuries.
How does it work?
Explore the city on foot solving puzzles based on real historical facts. No locked room — the city is your playground.
No app to download. Play directly from your browser. Guided step by step, at your own pace.
One purchase per phone is enough. Play with family, friends or as a couple — everyone participates.
Point your phone at the façade: a historical character appears and speaks to you in your language. Golden letters magically write themselves on the wall to reveal the puzzle answer.
Stuck? Progressive personalised hints. The character repeats the puzzle on demand — at your own pace.
French, English, German, Spanish, Italian + 27 other languages auto-translated by AI.
The game downloads to your phone on start. Once the "✓ Downloaded" indicator appears, everything works without data — narration, AR, GPS and puzzles. Perfect abroad without a data plan.
Want to go deeper?
Places tied to your adventure — optional entries, totally up to you · per person
The Route
5-10 curated sites across the territory
The gameplay: AR, camera, hidden clues
At each stop, open your phone camera: an augmented reality character appears on the façade and speaks your language. Hunt the clue — it materializes as golden letters on the real wall or floats in front of you. When you find it, the phone vibrates, an AR chest opens and reveals your answer fragment. 8 stops, 8 clues to find with the camera, 1 final code.
The stops on your route are a surprise. You'll discover them one by one, guided by your phone, starting from the meeting point.
How does it work with a group?
One phone = one team. Pick the number at checkout (1 to 10).
Solo, or a group sharing the screen. One team, one code.
Family, couple, or 2-3 teams competing. Each phone has its own code and its own score.
Friends, bachelor/bachelorette, small office outing — each their own code, each plays at their own pace. Tiered pricing then €6 flat per phone from the 6th.
- ✓All codes are independent — play at the same time OR separately, each team advances at its own pace.
- ✓Leaderboard between your teams + global game leaderboard — each score appears in the public ranking.
- ✓More than 10 phones or need a personalized quest? Discover custom tours.
Ready to live this adventure?
Get my code · 14,90€No calendar booking. Code sent immediately by email.
🔒 Secure payment · Code in 5 min · Free cancellation
Practical info
Why this route?
Military architecture
Towers, ramparts and medieval gates reveal Berchtold IV's strategic secrets
Hydraulic engineering
Bridges, fords and secret passages over the Sarine in 12th-century urbanism
Urban planning
The revolutionary geometric plan of medieval Fribourg
Sur les traces du fondateur
Berchtold IV et l'art de contrôler une rivière
9 features nobody else has
OddballTrip combines gamified play, augmented reality and AI. All our competitors deliver 1 or 2 of these angles. We deliver all 5.
AR treasure chest
A golden chest floats in front of the monument. Tap → opening animation → reveals a secret message.
AR narrator character
Point your phone at the façade: a knight, witch, monk, sailor, detective or ghost appears full-screen and speaks to you in your language with their dedicated ElevenLabs voice (each character has their own unique voice) — your living guide.
Magic golden letters
At the puzzle climax, golden letters magically write themselves on the real wall — that's the puzzle answer. An unforgettable visual effect.
Written + audio narration
Every puzzle available as text AND voice-over: read at your own pace or listen eyes-free while walking. Great in groups and for accessibility.
360° radar + vibration
A mini-radar shows the target even behind you, and the phone vibrates when you aim in the right direction.
Heritage storytelling
Every puzzle weaves in real historical facts (architecture, era, anecdotes). You learn by playing — like a gamified audioguide.
Progressive AI hints
3 levels of AI-generated help: vibe → where to look → answer format. You're never stuck.
AR selfie memento
At the end of the game, capture a selfie with OddballTrip banner + mascot, shareable on Instagram, TikTok.
Zero app to install
PWA technology: open the link, it plays in your browser. Same quality as an app, no App Store hassle.
Frequently asked questions
Q01Do I need an app or a paper guide?
Neither. Everything plays in your browser (Safari, Chrome) after you tap your activation link. No PDF to print, no download. The trail lives in your phone, that's it.
Q02How many stops are in Berchtold's Secret — The Hidden Passages of Medieval Fribourg?
Eight stops total. At each stop you find a camera clue, solve the puzzle, collect a fragment of the final code. With all eight, you've got the answer.
Q03Can we do Berchtold's Secret — The Hidden Passages of Medieval Fribourg as a family with kids?
Yes, from age 6 with an adult reading puzzles aloud, and from age 12 on their own. Kids love the "find the camera clue" part — it's very visual, gets them genuinely involved.
Q04What's the best time to start?
Morning between 10 and 11, or early afternoon around 2 PM, is ideal. You still have daylight ahead, Old Town of Fribourg, Switzerland is less crowded, and the light is better for camera clues.
Avis des aventuriers
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Your turn to play
Remontez aux origines de Fribourg et percez les secrets hydrauliques de Berchtold IV. Entre tours médiévales et ponts sur la Sarine, reconstituez le plan défensif le plus audacieux du XIIe siècle suisse.
1 purchase = 1 phone. Play several on the same device.
No calendar booking. Code sent immediately by email.
🔒Secure payment · Code in 5 min · Free cancellation
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