# 数独城 vs GrowBrain

数独城 and GrowBrain are too close to call on the numbers: across 6 compared parameters — price, update cadence, ads and in-app purchases among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Both are free to download. 数独城 sells 5 one-off in-app purchases and GrowBrain sells 6 in-app purchases, starting at $5.99 per month. Whichever you choose, the download price is not the number that matters.

数独城 ships an update every 9 days, GrowBrain fortnightly. The most recent releases landed on August 25, 2026 and August 18, 2026 respectively.

## The numbers

| Metric | 数独城 | GrowBrain |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 9 days** | Fortnightly |
| Size | 28 MB | 78 MB |
| Requires iOS | **15.0** | 16.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [正旋 金](https://appshunter.io/developer/1452746772) | [Roman Shulha](https://appshunter.io/developer/1798080275) |

## What reviewers say

### 数独城

[App page](https://appshunter.io/ios/app/id1670078749)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 数独币100枚 | $0.99 | one-time |
| Unlock all levels | $0.99 | one-time |
| 解锁模式avatar | $0.99 | one-time |
| 解锁模式color | $0.99 | one-time |
| 100 correction opportunities | $1.99 | one-time |


### GrowBrain

[App page](https://appshunter.io/ios/app/growbrain/id6742379010)

**Features:** Family Sharing

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 1-month subscription | $5.99 | per month |
| 1-month subscription | $5.99 | per month |
| 6-months subscription | $29.99 | per 6 months |
| 6-months subscription | $29.99 | per 6 months |
| 1-year subscription | $47.99 | per year |
| 1-year subscription | $49.99 | per year |


## Frequently asked questions

### Is 数独城 free?

数独城 is free to download, with in-app purchases available.

### Is GrowBrain free?

GrowBrain is free to download, with in-app purchases available.

### Do 数独城 or GrowBrain have ads?

Neither 数独城 nor GrowBrain shows ads.

### Which is updated more often, 数独城 or GrowBrain?

数独城 ships an update every 9 days, and GrowBrain fortnightly. Most recently, 数独城 was updated on August 25, 2026 and GrowBrain on August 18, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*