CERT is an explorable puzzle book. Discover a surreal, dreamlike world filled with classic deduction-based paper puzzles!

Made in 48 hours for Ludum Dare Compo 54.


How to play:

  • If you're playing on itch.io:
    • Use the embedded pdf.js viewer above.
    • The "pen" icon lets you draw on the document. Once you've drawn something you can drag it around the page, which is useful for placing things on grids.
  • If you’re playing using a downloaded file:
    • Download the "PDF (Facing Pages)” link.
    • For the best experience, open the PDF in a viewer that lets you draw and scribble on the document.
    • If you can’t do that, I recommend using a pencil and paper to draw out the puzzles and make notes.
  • If you’re printing the book on a home printer:
    • Download the “PDF (Facing Pages)” link.
    • These double pages are designed to print on A5 sheets.
    • If you only have A4 paper you can either scale them up or print two-to-a-page (if you do the latter I recommend cutting the sheets in half to avoid accidental spoilers).
  • If you’re printing the book through a printing service:
    • Download the “PDF (Single Pages)” link.
    • This document is intended to be printed as an A6 booklet.
    • Bleed margins are not included.

Updated 25 days ago
Rated 4.9 out of 5 stars
(14 total ratings)
GenrePuzzle, Adventure
Tagsadventure-game-book, Ludum Dare 54
Average sessionAbout a half-hour
AccessibilityColor-blind friendly, High-contrast
LinksLudum Dare


PDF (Facing Pages) 4 MB
Version 2 Oct 02, 2023
PDF (Single Pages) 4 MB
Version 2 Oct 02, 2023


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Thank you. I really enjoyed it. I give it a 5 out of 5 trigons :P


This game reminds me of those "Choose your own adventure" games.

It was fun, and i felt like the difficulty/learning curve was perfect!

I also like the Portal easter egg!


such a delightful and fun premise, i wish there were more puzzle books like this.


Oh, this is great.


That was great! 

I'd love to play another puzzle adventure like this, are there any that inspired you or that you'd recommend?

(1 edit) (+2)

Thanks! As far as I know mine is the first puzzle book to combine modern puzzles with exploration/adventure book gameplay - that’s why I wanted to try it!

For a similar style of “puzzle books with very light story” I can recommend Blaž Urban Gracar‘s “Lok” and “Abdec” books, both of which were definitely influences on this, but they don't have much of an adventure element.






Thanks for the suggestions! 

To give you more feedback: The branching paths and the "meta" layer of going back to find 'the space between' were fantastic ideas. These puzzles remind me of playing the game 'The Witness'

I completed it the recommended (?) way, and I'm glad I didn't find the second path (15 > 28) to the ending which would skip a puzzle or two. I wonder if a 3rd path could be created from using the unused letters from all of the puzzles combined. 

I wish I was more careful when checking my answers in the dictionary, as I spoiled at least one answer by seeing a future word in my peripheral. The word descriptions were great BTW. 

I felt one word was unintuitive (finis) - every other answer created a commonly known word (except gae but there was an alternative). Overall, would highly recommend. 

(1 edit)

Maybe spoilers below?








I agree with you about FINIS being unintuitive. I Thought it was trying to say FINISH, and that I somehow missed the H.

However, I interpretted GAE as an alternate spelling of gay. I don't know what the definition of it is referring to though.

Also, since you mentioned "The Witness", you might also like "The Looker". It's not as long, but it's a fun parody of "The Witness", with a similar art-style & gameplay mechanics!

That's very fair; those words are both bending the rules slightly, since they're really loanwords from other languages (Latin and Irish respectively) which are only used in English in quite specific circumstances.


this was really cool! I wish it ran me around more than the couple puzzles it took me to beat it. I went back through and did most of them though :) 

(1 edit) (+1)

Do not mind that last comment, I was just being a little delusional.
Very nice puzzles, short and sweet.

Huge thanks for the puzzles.