Shipping a puzzle where one shape doesn't quite fit: Off By One

Off By One started from a single premise: what if the whole game was just "find the one that's off"?

A grid of geometric shapes, all nearly identical. One has a subtle difference — a slight rotation, a fractional size variation, a decoration that breaks the pattern. Your job is to spot it. That's the game.

Why no timer

Almost every puzzle game reaches for a timer as its primary difficulty lever. We deliberately left it out. The appeal here is the slow scan — letting your eyes move across the grid until something catches. A countdown clock turns that into a different, worse experience.

The result is unusually quiet for a mobile game. You pick it up, look at shapes for a while, find the odd one, move on. No streak to protect, no lives to refill.

The procedural system

The shape-and-decoration combinations are generated procedurally in SwiftUI Canvas. Each puzzle draws from ~133,200 possible combinations, so the same stage presents a different layout each time. 35 stages across Easy, Normal, and Hard. Game Center tracks 17 achievements.

One honest limitation

The App Store gives you 6 seconds of preview video. Off By One is genuinely hard to explain in 6 seconds. A screenshot shows a grid of geometric shapes — accurate, but not illuminating. The experience is in the sustained, quiet looking, and that doesn't compress well into a thumbnail or trailer.

No in-app purchases yet either. Rewarded ads only, which means we haven't built a clear path for players who'd happily pay to remove them.

Try it

Free on iOS 16+.

https://apps.apple.com/jp/app/id6762133251

If you build puzzle games: curious how you've handled previewing "quiet focus" experiences in the store listing. It's the hardest part.