Luxembourg City — Citadel's Code
Uncover the hidden code behind the 1867 Treaty of London that forced the demolition of Europe's strongest citadel. Decode clues at forts and ramparts to expose the Prussian plot and diplomatic betrayal.
📱 1 to 10 phones · 1 team per phone · Independent codes
In 1867, the Treaty of London compelled Luxembourg to dismantle its mighty Bock Casemates and surrounding fortresses—the most impregnable defenses in Europe—without a single shot fired
Luxembourg City — Citadel's Code
You are an archivist-cryptographer, tasked by Grand Duke Henri to authenticate a forgotten 17th-century document, discovered in the cellars of Luxembourg City Hall.
This parchment,
Delve into the millennia-old layers of Luxembourg City, from Roman foundations to European institutions, to decipher a code that could rewrite its history.
« The State of Luxembourg is a buffer state, a state whose destiny is to serve as a battlefield. »— Victor Hugo, Choses vues, 1867
The story that haunts this land
Your investigation begins at Luxembourg City Hall, on Place Guillaume II. Inaugurated in 1838 and built on the remains of an old Franciscan convent, this neoclassical building is the administrative heart of Luxembourg City. It is here that the initial parchment was discovered, beneath a basement slab. You search for the first marks, symbols engraved in the limestone foundations, which could be the entry keys to the code. The square itself, named in honor of King William II of the Netherlands and Grand Duke of Luxembourg, is a historical convergence point for Luxembourg's heritage.
A few steps away, the Grand Ducal Palace, the official residence of the Grand Duke of Luxembourg, awaits you. A former City Hall until 1795, then the prefecture's seat during the French occupation, it embodies the political transformations of the region. The document mentions events related to the Thirty Years' War and 17th-century Spanish fortifications, a period when Luxembourg was a strategic stronghold. The Renaissance facades of the Palace, restored in the 19th century, may conceal messages in their ornaments, clues hidden by the master builders of the time.
Place du Marché-aux-Poissons, the historical birthplace of Luxembourg City, is your next stop. It was here, on the Bock, that the first castle of Count Sigefroi was erected in 963, marking the city's birth. The parchment evokes a map of the underground passages, the casemates, which would start from this area. You examine the cobblestones and ancient walls, looking for marks that would correspond with the fragmented sketches in the document. This site is a direct window into Luxembourg's medieval history and defensive evolution.
Your quest then leads you to Notre-Dame Cathedral in Luxembourg. Built by the Jesuits between 1613 and 1621, its architecture combines late Gothic and Renaissance styles. The code seems to refer to religious symbols and heraldic figures present in the stained glass windows and sculptures. You decipher the motifs, looking for correlations with the alchemical glyphs on the parchment. The crypt, where members of the grand ducal family rest, is a place of secrets and history, a central point for Luxembourgish heritage.
The route ends near Luxembourg Station, a symbol of the city's modernity and openness in the 19th century. After crossing the Passerelle and observing the Gëlle Fra, a memorial to Luxembourgish soldiers, then the BCEE headquarters, you have assembled the different pieces of the code. The clues collected at the City Hall, the Grand Ducal Palace, Place du Marché-aux-Poissons, and Notre-Dame Cathedral converge here. You have reconstructed the meaning of the parchment and understood its role in the history of Luxembourg City's fortifications. This exploration has offered you an understanding of the past, from the city's foundation to its contemporary role at the heart of Europe, thus enriching your perspective on Luxembourg.
A game, a guided tour and a heritage guide — all in one
You're not just buying an escape game. You're carrying a living guide — historical anecdotes, forgotten legends, key monuments, hidden architecture — unfolding as you go.
At each stop, places ordinary guides miss — secret façades, sculpted crests, alleys steeped in history.
Every riddle is rooted in a real historical fact or local legend. You leave with dozens of stories to tell.
Learn to read buildings — flamboyant Gothic, Baroque, Art Deco — like a real art historian, while having fun.
Walk through the city like a novel's character — every alley becomes a stage, every square a theatre.
A voice walks with you at every step, tells the story of each place, reads clues, adds a cinematic feel.
Keep access to the guide & game for 1 year. Come back any time, share it with friends.
« You will not leave this city the way you entered it. »
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
8 stages through the city
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 · 12€No calendar booking. Code sent immediately by email.
🔒 Secure payment · Code in 5 min · Free cancellation
Practical info
Why this route?
Historic Treaty
Dive into the heart of the 1867 Treaty of London that reshaped the map of Europe.
Diplomatic Intrigue
Identify a double agent whose revelations influenced the fortress's fate.
European Powers
Explore the tensions and alliances between Bismarck, Napoleon III, and William III.
The fate of a nation, sealed by a secret treaty.
Your mission: reveal the hidden truths behind the fortress's dismantling.
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
Q01Is Luxembourg City — Citadel's Code similar to a treasure hunt?
Same spirit: search, deduce, find. But here the "treasure" is a full story to piece together in eight stops. Each stop gives you a fragment of the final code. Eight fragments later, you've cracked it.
Q02How many stops are in Luxembourg City — Citadel's Code?
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 play Luxembourg City — Citadel's Code as a couple?
Great two-person format. Narration is dramatic without overdoing it, puzzles are designed to spark conversation. Ideal for new relationships or anniversaries — you discover the city and coordinate on puzzles simultaneously.
Q04What if we get stuck on a puzzle?
Three hint levels per puzzle, with a small increasing time penalty. If truly stuck after level 3, you can skip the step (45-min penalty). The point: nobody stays blocked and goes home frustrated.
Avis des aventuriers
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Your turn to play
Delve into the millennia-old layers of Luxembourg City, from Roman foundations to European institutions, to decipher a code that could rewrite its history.
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
🪙+24 TripCoins granted with your booking
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