Questions and answers
obsQRity™ is pronounced "obscurity."
What is obsQRity™?
A daily puzzle played on a real QR code. QR codes are built to survive damage, and the game is finding out how much. Each move, you tap a light area of the QR code and it fills in dark. Your score is how many safe moves you make before the QR code stops working.
Is it really a real QR code?
Yes! Every puzzle is a working QR code, and it stays one while you play, right up until you break it. Point your phone's camera at it and it opens that puzzle's own link, like obsqrity.com/1.
Why does a damaged QR code still work?
QR codes are designed with Reed-Solomon error correction, the same math that lets a scratched CD keep playing. The code stores extra information so it can rebuild what's missing. But there's a limit, and it's an exact number: lose more than that and the code can't be read anymore. That limit is what you're playing against.
What's a brick?
A QR code stores its data in bytes: each square is one bit, and 8 squares make a byte. In the game I call them bricks. Damage any square in a brick and that whole brick counts as damaged. Each puzzle tells you how many bricks it can lose, and if you go one past that, the code breaks.
What's a free move?
A move only costs you the bricks it newly damages. So if an area sits completely inside bricks you've already damaged, it's free. The dotted timing strips between the big corner squares on a QR code are there to help your phone count rows and columns. They aren't bricks at all, so areas on them are free too, unless they spill into a brick.
Why are some areas pink?
Pink areas are out of bounds. They're parts of the code that tell your phone where the code is and how it's set up. Damage them and it won't scan no matter how careful you are, so the game walls them off.
How do you know the maximum?
For every puzzle, a computer works out the exact best possible game: the most safe moves anyone can make. Then we check that result with real QR code readers to make sure the code still scans. So the max isn't a guess. If you hit it, that's a perfect game.
Can't I just play this on paper?
Yes, absolutely, and that's how it started! Print out and draw on a QR code, fill in one area at a time with a pen, and scan it with your phone after each move. If it still opens, the move was safe. Your phone is the referee.
What paper can't tell you is the best possible result. Picking which areas to fill so you get the most moves without breaking it is a hard math problem: the number of combinations explodes quickly. We solve that for every puzzle so you have a real target to aim for. Paper also doesn't show you the bricks, so it's like playing on Hard.
Can I use it to teach?
Yes, and I'd love that. obsQRity is a hands-on way into a few big ideas:
- Bits and bytes: every square is a bit, and each brick is a byte. Filling in a single square is a bit flip, the most basic form of data corruption.
- Reed-Solomon error correction: invented by Irving Reed and Gustave Solomon in 1960, it's why a QR code still works with part of it missing. The same codes protect CDs and DVDs, and they carried pictures home from the Voyager space probes. Every puzzle shows exactly where that protection runs out.
- Optimization: finding the best result under a fixed budget, the kind of problem computers solve with integer programming. That's how the max for each puzzle is found.
It works on paper too: print a code, let students fill in areas with a pen, and scan after each move to see if the code survives. If you use it in a class, I'd love to hear how it went at hello@obsqrity.com.
When does a new puzzle come out?
Every day at midnight, your time. Sundays bring a bigger QR code.
What do the difficulty levels change?
Only what you can see. Easy shows the bricks in color. Medium hides them, but you can peek. Hard is just the QR code. Nightmare is Hard with a clock. The puzzle itself is the same at every level.
How is Sunday's puzzle different?
It's a larger QR code, 25 squares across instead of 21, with 44 bricks instead of 26. It also has a small helper square near one corner with a pink ring. That's out of bounds too. The bricks have to bend around it, so Sunday bricks come in odd shapes, making the strategy and layout trickier. More bricks also means a longer game, but the rules remain exactly the same.
Can I play it again?
Sure, tap Play again. Your first finished game of the day is the one that counts and the one you share.
Is it free? Do I need an account?
It's free, and there's no account or sign-up. It runs right in your browser. Your scores and streak are saved on your own device.
Who made it?
I did! I'm Patrick Keane, and I came up with obsQRity at my kitchen table, scribbling on a newspaper ad early one morning. You can find me on LinkedIn.
How do I get in touch?
Email hello@obsqrity.com or follow @obsqrity on X. I'd love to hear what you think.