We shipped a one-mechanic puzzle app — here's what we built and where it falls short

#ios #swift #gamedev #indiedev

The premise

Most mobile games compete on stimulation: timers, streaks, daily missions, push notifications. We wanted to go the opposite direction.

Off By One has exactly one mechanic: a grid of near-identical geometric shapes, one slightly wrong. Find it. No countdown. No lives. No nudge to come back tomorrow.

How it works technically

Drawing is handled by SwiftUI Canvas. Shapes and decorations are procedurally generated — around 133,200 combinations — so the same stage looks different on each attempt. 35 stages across Easy, Normal, and Hard. 17 Game Center achievements for players who want a concrete goal. iOS 16+ required.

The variation isn't cosmetic. On Hard, the grid is dense enough that the wrong shape can sit unnoticed for a while. Increasing grid density was the primary difficulty lever.

What works

Players who sit with it tend to describe it as calming — which was the exact feeling we were building toward. Removing urgency mechanics changes the texture of the experience more than we expected. The procedural generation also means replay doesn't feel stale.

The single-mechanic constraint kept scope manageable. The app does one thing consistently.

What doesn't (yet)

The honest problem: a 6-second App Store preview video can't convey quiet observation. The video reads as "shapes on a screen" and people scroll past. Discovery is the hard part, not gameplay.

In-app purchases aren't implemented. The app is free with rewarded ads, which is fine for users but limits what we can do on the revenue side.