About Protracto
Protracto is a daily spatial reasoning puzzle that challenges you to find a secret angle - not by typing a number, but by physically forming it. Using two adjustable lines, you position them to match what you think the hidden angle is, submit your guess, and receive a simple hint: go higher or lower. Each day brings a new secret angle, shared by every player around the world, resetting at midnight UTC.
Why We Created Protracto
We noticed that every angle guessing game on the internet was essentially the same: an angle appears on screen, you type a number, you are told if you are right or wrong. The challenge was always one of recognition - can you identify what you are looking at?
We wanted to flip that. What if the angle was hidden, and the challenge was to discover it rather than identify it? What if instead of reading an angle on screen, you had to work your way towards it? That question became Protracto.
The drag interaction also made the game feel more tactile and deliberate than typing a number ever could. There is something satisfying about using two lines to set an angle, committing to an angle, and discovering how close your spatial instincts actually are. We think that experience is what makes Protracto genuinely different from anything else in this space - and we hope you agree once you play it.
How To Play Protracto
When you arrive at Protracto, you will see two lines sitting on top of each other at the centre of the screen. Move the top line away from the bottom line to open up an angle. Once the lines are separated, you can adjust either line independently using the anchor circle at the end of each one. When you are happy with your guess, hit Submit.
After each submission, you will be told whether the secret angle for the day is higher or lower than your guess. Use that feedback to adjust your next attempt, narrowing in on the answer with each guess until you find it or run out of attempts.
There is no degree number shown while you adjust. That is intentional. Protracto is a test of spatial reasoning, not arithmetic, and showing you the number would turn it into a very different - and much easier game.
Frequently Asked Questions
What is Protracto?
Protracto is a free daily angle puzzle where you find a hidden secret angle by dragging two lines rather than typing a number. A new angle is chosen every day and is the same for all players worldwide.
How is Protracto different from other angle guessing games?
Every other angle guessing game shows you a drawn angle and asks you to identify it by entering a number. Protracto does the opposite - the angle is hidden, and you position two lines to form your guess. It is a test of spatial reasoning rather than number recognition, and the drag interaction makes it a fundamentally more tactile and satisfying experience.
Is the angle the same for everyone?
Yes. The same secret angle is shared by every player around the world each day. The puzzle resets at midnight UTC, so everyone is always working on the same challenge regardless of where they are.
How many attempts do I get?
You get a total of 9 attempts. This is based on Binary Search theory to yield the ideal number of attempts to solve the puzzle.
Can I play past puzzles?
Yes. The Archive section contains every Protracto puzzle from the day we launched. Each past puzzle can be replayed in either Easy or Hard mode, and your results are saved so you can see which ones you have already solved.
Does the puzzle reset every day?
Yes. A new secret angle is generated every day at midnight UTC. If you have not played today's puzzle yet, it will be waiting for you when you arrive.
What does the angle indicator show?
The amber arc between the two lines shows you the current angle you have constructed visually. It does not show a degree number - that would make the game too easy. The arc is purely a visual aid to help you see the shape of the angle you are forming.
Can I share my result?
Yes. Once the puzzle is complete, a Share button appears that generates a simple result card showing your guess sequence and the number of attempts you used. You can share it directly or copy it to your clipboard.