土を、光らせる。
Tsuchi o, hikaraseru. — Make dirt shine.
A quiet iPhone game about the shiny mud ball every Japanese kid once made: schoolyard dirt, a little water, patience, and a glass bottle. Built for the grown-up who remembers that afternoon.
No coins. No timers. No failure screens. Bad technique makes an uglier ball — never a game over.
The afternoon, again
You find ordinary dirt — in its own place: beside the schoolyard's chalk line, on the riverbank, between the field furrows. You make a fragile, ugly lump. You keep correcting it — pack, dust, rest, burnish. The surface slowly hardens, and the shine appears because you were careful. It is the same small discipline you had at seven, when the drawer of your school desk held something round and secret.
At the reveal, the kid next to you leans in: 「けっこう光ってんじゃん」 — "That's pretty shiny, actually."
A child's hands, an adult's patience
子どもの泥だんご
The childhood ballCollect dirt where it lives, pick it clean, stir the mud, pack it round, dust on さら粉 shell layers, rest it in a plastic bag, burnish with a glass bottle — everything a kid actually did. You can call it done here, with a genuine schoolyard shine.
≈ 4 minutes大人の仕上げ
The grown-up finishSeparate fine clay — jar, settle, pour, dry, grind, sieve — then lay whisper-thin coats and polish with cloth until the ball holds a reflection. The mirror finish an adult finally has the patience for.
Full session ≈ 5–8 minutesOne continuous evening
The early steps share a single persistent 3D world in warm dusk light — the camera glides between collecting, cleaning, and mixing, and the ball is lifted, still wet, out of the mixing bowl. Every surface is procedural; there are no art assets anywhere in the app.
What makes it different
- Gesture-first, tool by tool. Drag the mound to gather soil, flick pebbles off the heap, turn the bowl to check behind, hold the water cup, stir, press to pack, dust and rub shell layers, and guide a green ramune bottle around the ball in slow circles.
- Cracks are never a dead end. The real schoolyard repair: a damp thumb rubbed over the crack closes it, at a small cost in shine. The first crack teaches you how.
- The ball waits for you. The in-progress ball is saved continuously, and the title offers つづきから — picked back up exactly where it rested, like the real thing in a desk drawer.
- A synthesized dusk. A distant cicada wash with falling higurashi calls, water drops, glass glide, cloth — and the school chime at the reveal. Every sound is generated in code.
- A shelf that matters. Finished balls persist and sit on wooden planks as true 3D renders, each with its own name, score, and memory.
「うわ、鏡みたい……さわらせて！」 — the friend, when the ball scores high enough
For the curious and the press
| Platform | iPhone · iOS 17.0+ · portrait |
| Engine | Swift, SwiftUI, SceneKit — fully procedural art & audio |
| Session length | 4–8 minutes per ball |
| Business model | Pay once. No ads, no in-app purchases. |
| Privacy | Data Not Collected — see the privacy policy. |
| Languages | Japanese-led bilingual — 日本語 first, English beneath, one build |
| Support | Support page · kern.konrad@gmail.com |