# RYUKIN vs PrimeFactorizationGame

The clearest difference is price: PrimeFactorizationGame at Free against RYUKIN's $3.49. PrimeFactorizationGame also leads on in-app purchases (none vs 38). RYUKIN's advantage is ads (none vs shown) and update cadence (every 5 days vs monthly). On device support and iOS requirement there is nothing between them.

PrimeFactorizationGame is free to download; RYUKIN costs $3.49 up front. RYUKIN sells 35 one-off in-app purchases. PrimeFactorizationGame asks for nothing beyond the download.

RYUKIN ships an update every 5 days, PrimeFactorizationGame monthly. The most recent releases landed on October 10, 2026 and September 28, 2026 respectively.

## The numbers

| Metric | RYUKIN | PrimeFactorizationGame |
| --- | --- | --- |
| Price | $3.49 | **Free** |
| Rating | **[4.9 (60 ratings)](https://appshunter.io/ios/app/ryukin/id6471839445/reviews)** | — |
| Number of ratings | **60** | — |
| Positive reviews | 94.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | **Every 5 days** | Monthly |
| Monetization | Free with in-app purchases | — |
| Size | 225 MB | 7 MB |
| Requires iOS | **16.0** | 17.6 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Masataka Hakozaki](https://appshunter.io/developer/323346554) | [TomatoAppLab](https://appshunter.io/developer/1676711750) |

## What reviewers say

### RYUKIN

[App page](https://appshunter.io/ios/app/ryukin/id6471839445)

Experience the serene beauty of goldfish swimming in a customizable virtual aquarium. Interact with the fish, adjust tank settings, and enjoy soothing visuals and sounds. Perfect for relaxation or a calming presence.

**Highlights:** Interactive goldfish that respond to touch, Customizable tank shape and background, Soothing water sounds and visuals, Cat & Baby Mode for safe interaction, Sleep timer for bedtime use, Play your own music, Clock and date display

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

**In-app purchases (35)**

| Purchase | Price | Billing |
| --- | --- | --- |
| WIREFRAME RAINBOW | $0.99 | one-time |
| ROBO FISH 02 | $1.99 | one-time |
| ROBO FISH 04 | $1.99 | one-time |
| ROBO FISH 06 | $1.99 | one-time |
| GHOST BRIDE | $1.99 | one-time |
| BAT FISH | $1.99 | one-time |
| CALICO ORANGE/WHITE/BLACK | $1.99 | one-time |
| BLACK WHITE KITTY FISH | $1.99 | one-time |
| GHOST TRANSLUCENT | $1.99 | one-time |
| BLACK KITTY FISH | $1.99 | one-time |
| WHITE KITTY FISH | $1.99 | one-time |
| ROBO FISH 03 | $1.99 | one-time |
| GHOST BLACK | $1.99 | one-time |
| ROBO FISH 01 | $1.99 | one-time |
| ORANGE & WHITE KITTY FISH | $1.99 | one-time |
| RED RYUKIN | $1.99 | one-time |
| RED-WHITE RYUKIN | $1.99 | one-time |
| CALICO RED/WHITE/BLACK | $1.99 | one-time |
| ORANGE/WHITE | $1.99 | one-time |
| CALICO RED/GRAY/BLACK | $1.99 | one-time |
| YELLOW GOLD RYUKIN | $1.99 | one-time |
| RED CAP ORANDA | $1.99 | one-time |
| RED/WHITE II | $1.99 | one-time |
| LIONHEAD ORANGE/WHITE/BLACK | $1.99 | one-time |
| GHOST LUMINOUS | $1.99 | one-time |
| BLACK RYUKIN | $1.99 | one-time |
| CALICO KITTY FISH | $1.99 | one-time |
| GRAY WHITE KITTY FISH | $1.99 | one-time |
| WHITE VAMPIRE | $1.99 | one-time |
| BLACK VAMPIRE | $1.99 | one-time |
| BLACK WITCH | $1.99 | one-time |
| WHITE WITCH | $1.99 | one-time |
| ZOMBIE FISH | $1.99 | one-time |
| SKELETON FISH | $1.99 | one-time |
| PANDA TELESCOPE | $1.99 | one-time |

**What reviewers like**

- 💎 Gorgeous and lifelike fish
- 🎨 Beautiful and customizable environments
- 🎶 Soothing water sounds
- 🕰️ Useful clock feature
- 👍 Immersive and relaxing experience

**What reviewers complain about**

- 🔋 High battery consumption on max settings
- 💰 Additional fish require paid purchases
- 🌱 Lack of plant/natural decor options
- 🐟 Limited variety of standard goldfish

**Reported bugs**

- Occasional crashing on high-end devices

**Requested features**

- Ability to change fish colors
- Add more fish species (e.g. bettas, tetras)
- Implement fish breeding/growth mode
- Allow customizing fish placement in tank
- Add desktop/widget mode for always-on display


### PrimeFactorizationGame

[App page](https://appshunter.io/ios/app/primefactorizationgame/id6755812213)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is RYUKIN free?

RYUKIN costs $3.49, and also offers in-app purchases.

### Is PrimeFactorizationGame free?

PrimeFactorizationGame is free to download, with no in-app purchases.

### Do RYUKIN or PrimeFactorizationGame have ads?

PrimeFactorizationGame shows ads; RYUKIN does not.

### Which is updated more often, RYUKIN or PrimeFactorizationGame?

RYUKIN ships an update every 5 days, and PrimeFactorizationGame monthly. Most recently, RYUKIN was updated on October 10, 2026 and PrimeFactorizationGame on September 28, 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.*