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If you enjoy thrilling stories filled with riddles, codes, unknown symbols, ancient languages, conspiracy theories, and many other exotic secrets and mysteries, SEALED BOOK PROJECT is created just for you.

✔️ PLAY 100 % FREE ✔️

Vol. 1 PRAELUDIUM is the first multilingual adventure puzzle book-game of the series of interactive CHALLENGE BOOKS suitable for people of all ages who love the excitement of reading Mystery / Thriller / Suspense / Adventure novels.

The BOOK for readers, who love CHALLENGES!


There are riddles in the game, the answers to which are names of objects, institutions, terms, and others.
Translations into different languages can NOT be used to answer these riddles.
The answers must be entered in their original form and in the language of origin.


In the middle of the twentieth century, a representative of the two mightiest driving forces in society – the Church and Science – publicly announced that he had created something that had until then been considered unthinkable and impossible.
To the day he died this person never retracted his claim; moreover, many authoritative researchers in the field assert that this artifact does exist, even at this very moment, and is one of the most closely guarded secrets in human history. Where it is now and whether it has been used is anybody’s guess…
The story you are about to read offers just one possible version of what might have happened and may even be happening right now.
All places mentioned in PRAELUDIUM are real and exist to this very day.
Any resemblance to actual persons and events...could be accidental.

⚫️ What is a CHALLENGE BOOK?

In our CHALLENGE BOOKS, we offer a unique concept with which we want to challenge the readers by offering them the opportunity of personal involvement in the action by means of some special options for solving numerous puzzles, decrypt embroidered codes, rebuses, and ciphers, decrypt graphic images, musical and visual riddles that are an integral part of history.


1.🔸 A multidimensional concept, unique of its kind
The books we create are books with a difference. With them, you don’t choose the ending. The ending chooses you and challenges you to reach it. Can you do it?

2.🔸 Completely cost-free
Available for reading from the first to the last word, without you having to pay for anything.

3.🔸 Available in multiple languages

4.🔸 Inspired by a true story
The plot is inspired by documented events from the mid-20th century. In the course of the story, they will be enriched with many legends, mysteries, and puzzles, all of which derive from the beliefs of ancient peoples and ethnic groups.

5.🔸 Real places
All places where the action unfolds are absolutely real and exist to this day.

6.🔸 Graphics
We have created and chosen for our books special graphic visualizations with the aim of making you more fully part of the story.

7.🔸 Piano soundtrack
The piano music you’ll hear as you read has been played and recorded by us personally. Every single note, without exception.

8.🔸 Sound effects
To add further to the pleasure of the experience, we’ve created not only the piano music but also exciting sound effects which accompany some scenes in the story.

9.🔸 Intuitive approach
Everything in our applications is logically arranged and extremely easy to use, without the need to master any rules.

10.🔸 Special Extras
If you’re curious about these unique extras, go to the category EXTRAS in the application, familiarize yourself with them and allow the magic to happen.

⚫️ Follow us for the latest news and upcoming books:


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What's New

Bug fix
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Additional Information

May 23, 2020
Current Version
Requires Android
4.1 and up
Content Rating
Everyone 10+
Mild Violence
Interactive Elements
In-Game Purchases
In-app Products
$4.99 per item
Offered By
Sealed Book Project
Plovdiv 4003, Bulgaria, St. Botev 5
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