Comparison

RYUKIN vs PrimeFactorizationGame

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

RYUKIN

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
Read full description

~ Gracefully Fluttering Goldfish ~ Goldfish glide gracefully through crystal-clear water, their fins fluttering gently as they swim. Their charming gestures and soft, delicate fin movements have been carefully recreated. Enjoy the beauty of goldfish anytime, anywhere — without the need for water changes or feeding. App Highlights - Fish respond to your touch and follow your finger - Customize tank shape, background color, and floating objects - Soothing water sounds and clear, refreshing visuals - "Cat & Baby Mode" for safe play with kittens and toddlers - Sleep timer for relaxing bedtime use - Play your favorite music while watching the aquarium - Clock and date display - White and black goldfish included; colorful and themed fish available via in-app purchase Settings & Customization - Camera options (Free position / Follow fish / Auto-rotation) - Screen orientation - Tilt sensitivity - Sleep timer - UI size - Toggle water surface, bubbles, and other effects - Adjust brightness, saturation, contrast, and color tone - Quality settings (resolution and various effects) - Volume settings (water sounds, bubble sounds) - Clock & date options (font, position, size) Other Features - Fish, objects, and the water surface respond to touch and device tilt - Fish may whimsically swim toward your finger - Tap too much and the fish may faint! - Feed the fish - Adjust the size of fish and objects - Display up to six fish at once ‥∴ Bringing the Allure of Goldfish Closer ∴‥ This app was born from a childhood dream of recreating goldfish through programming. Fifteen years after the release of the original app *Wa Kingyo*, countless refinements have been made to capture the graceful and charming nature of these fish. From the gentle movement of their fins to the way they chase and munch on food, experience the beauty and warmth that goldfish bring. News and Support X: @m_hakozaki TikTok: @m_hakozaki Instagram: @masataka.hakozaki

About

PrimeFactorizationGame

Features
Read full description

Number meteors are coming! Break them apart with prime factorization! A brand-new brain training game that combines prime factorization with shooting action! Watch the number meteors falling from the sky, tap the correct prime number button, and fire your beam! Break down the numbers as fast as you can. The quicker you perform prime factorization, the faster the meteors shrink and eventually shatter! Train your calculation speed, mental math skills, and decision-making ability all at once. A full-fledged math and brain-training game that can be enjoyed by both kids and adults. [Features] ・Experience prime factorization like an action shooting game ・Quickly choose and destroy multiple falling meteors ・Difficulty levels from Beginner all the way to the super hard Oni mode ・Perfect for improving calculation skills, brain agility, and mental math ・Great for short brain-training sessions and math learning [Recommended for] ・Fans of math puzzles and number games ・Those who love brain training or calculation games ・Anyone who wants to improve their mental math speed ・Players who excel at fast-reaction games ・Parents looking for educational math games for kids Can your brain survive Oni mode? Aim to become the fastest prime factorization master!

Screenshots

RYUKIN4 screens
PrimeFactorizationGame3 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

UpkeepUpdate frequency

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

Scorecard4 real differences · 6 level
RYUKIN versus PrimeFactorizationGame: the parameters behind the verdict, then further details
ParameterRYUKINPrimeFactorizationGame
Price$3.49Free — better
Rating4.9 (60 ratings) — better—
Positive reviews94.0% of reviews—
Number of ratings60 — better—
Update frequencyEvery 5 days — betterMonthly
AdsNo — betterYes
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPadiPhone, iPad
Requires iOS16.0 — better17.6
Further details — not scored
Size225 MB7 MB
Age rating4+4+
DeveloperMasataka HakozakiTomatoAppLab

Bugs and requests

RYUKIN

Reported bugs

1 issue
  • Occasional crashing on high-end devices

Requested features

5 requests
  • 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

Not enough reviews yet to summarise bugs or requests.

In-app purchases

35 purchases

RYUKIN

One-time35
  • WIREFRAME RAINBOW$0.99
  • ROBO FISH 02$1.99
  • ROBO FISH 04$1.99
Show 32 more
  • ROBO FISH 06$1.99
  • GHOST BRIDE$1.99
  • BAT FISH$1.99
  • CALICO ORANGE/WHITE/BLACK$1.99
  • BLACK WHITE KITTY FISH$1.99
  • GHOST TRANSLUCENT$1.99
  • BLACK KITTY FISH$1.99
  • WHITE KITTY FISH$1.99
  • ROBO FISH 03$1.99
  • GHOST BLACK$1.99
  • ROBO FISH 01$1.99
  • ORANGE & WHITE KITTY FISH$1.99
  • RED RYUKIN$1.99
  • RED-WHITE RYUKIN$1.99
  • CALICO RED/WHITE/BLACK$1.99
  • ORANGE/WHITE$1.99
  • CALICO RED/GRAY/BLACK$1.99
  • YELLOW GOLD RYUKIN$1.99
  • RED CAP ORANDA$1.99
  • RED/WHITE II$1.99
  • LIONHEAD ORANGE/WHITE/BLACK$1.99
  • GHOST LUMINOUS$1.99
  • BLACK RYUKIN$1.99
  • CALICO KITTY FISH$1.99
  • GRAY WHITE KITTY FISH$1.99
  • WHITE VAMPIRE$1.99
  • BLACK VAMPIRE$1.99
  • BLACK WITCH$1.99
  • WHITE WITCH$1.99
  • ZOMBIE FISH$1.99
  • SKELETON FISH$1.99
  • PANDA TELESCOPE$1.99
None

PrimeFactorizationGame

No in-app purchases

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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