Sumi Mahjong · Art IAP is part of Hooosberg's public product diary for Sumi Mahjong. It turns a real build step into a searchable case study for international readers.
A quiet iPhone tile-matching game with hand-tuned ink tiles, offline play, and optional one-time theme unlocks.
The original Chinese article was published on 2026-06-15 under App Store. It focuses on 免费完整玩法加一次买断主题，把美术工作流和 IAP 设计放进同一个体验边界里。
The reusable learning angle is iOS small game, StoreKit 2, No-ads product design, Multilingual launch. The diary format is deliberately practical: context, decision, implementation boundary, review impact, and what another builder can reuse.
This English page is generated from the same public product facts as the Chinese site. It is meant to be indexable and useful now, while still leaving room for later hand-polished translation of the full Chinese narrative.
Context
This entry belongs to the Sumi Mahjong build series. It should be read as one stage in a larger product journey, not as an isolated announcement.
The site keeps success cases and failure cases together because both create reusable judgment.
Implementation boundary
Relevant product capabilities include 144 hand-tuned ink Mahjong tiles, Classic two-turn matching rule, Undo, hint, and shuffle, No ad SDKs, accounts, or third-party tracking. The diary explains how these capabilities are selected, constrained, reviewed, or turned into launch material.
Privacy and trust
Normal play does not require network access. Optional purchases are handled by Apple StoreKit.
For an indie product matrix, trust is built through many small facts: local data boundaries, review status, support links, honest postmortems, and stable canonical pages.
What another builder can reuse
Another builder can reuse the pattern: start with a narrow product promise, make the privacy boundary inspectable, connect every public page to a real download or repository, and turn the launch process into a searchable article.
That is why the diary sits next to the product page. The product builds trust, and the diary teaches the path that made the product possible.