Comparison

What the Shell vs Zero21 Card Game

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

Head to head
About

What the Shell

Experience a unique twist on a classic board game where both players move simultaneously and secretly. Outwit your opponent by capturing pieces, hatching eggs, and strategically lining up five in a row. Enjoy face-to-face play, online matches, or offline challenges.

Highlights
  • Simultaneous secret moves
  • Piece capture mechanics
  • Egg hatching and capture
  • Local and online multiplayer
  • Offline AI opponent
  • Controller support
Features
Read full description

You both move at the same time, in secret. Only when the turtles land do you find out whose plan just fell apart. Oh no — this ain't your traditional five-in-a-row. What the Shell is the one you reach for when you and a friend are bored on the couch: "Wanna play What the Shell?" A game between two beginners can be over in three minutes, and somehow you're still at it two hours later, laughing every time your minds collide and another egg turns up on the board. "Simultaneous play boosts the fun of this intuitive, yet surprisingly deep board game." — Matthias Titze, Clarc producer (German Computer Game Award winner) There's no taking turns, and nobody goes first — so nobody gets the first-player edge. You lock in your move, your friend locks in theirs, and the board resolves both at once. Strategy still wins games, but you're up against a mind you can't see, and you never know where she just played. Sandwich two of their turtles and they're gone. Both reach for the same square and your turtles crash into an egg — and an egg is a curious thing: you can capture it, or hatch it. One bold move flips a game you'd already written off. Capture at the right moment and a chain reaction can tear through the position your friend spent the whole game building. It's never won or lost until the last move. Made for two: • Sit down together, each on your own phone or tablet, and battle it out face to face — best enjoyed in the same room • Or play online at your own pace, whether your friend's across town or across the world • No one around? Tap Quick Match for a random opponent, or take on the panda offline, from an easygoing Newcomer to a tough Expert • Got a controller? Connect it to your iPad or iPhone and play however you want Read the board, then read your friend. Capture a couple of turtles, deal with the eggs, line up five in a row — and enjoy the look on his face when it all comes together.

About

Zero21 Card Game

This number puzzle game challenges you to keep your score between 0 and 21 by collecting cards. Utilize power-up cards and strategic choices to navigate diverse levels and daily challenges. It's a fun, relaxing way to train your brain.

Highlights
  • Keep score between 0 and 21
  • Collect number cards
  • Use power-up cards
  • Unlock new card collections
  • Daily challenges
  • Diverse card layouts
Features
Read full description

"ZERO21 CARD GAME Zero21 Card Game is a number games with solitaire card. It is fun, relax but helps to train your brain. ***HOW TO PLAY*** The game rule is simple: Try to stay between 0 and 21. - Collect the number card on the board - Choose the right one to keep the sum lower than 21 and greater than 0 - Use the power up cards to help you solve this math game ***FEATURES*** - PICK YOUR STYLE: Many unique stylish card collections for your choice to play to keep things fresh everyday. - AMAZE IN EVERY LEVEL: Diversity card layouts at each level let the game more interesting. - FINISH DAILY CHALLENGE to unlock new card collections. - Golden card keeps your current number at the golden one. - See the next number with forseen card. - Hold button help to keep the card for the next move. - Remove the unused card with Delete button. You should not miss this mathgame because it is TOTALLY FREE and help you BE SMARTER everyday!

Screenshots

What the Shell4 screens
Zero21 Card Game4 screens

Verdict

The call

The clearest difference is review sentiment: What the Shell at 100% against Zero21 Card Game's 0%. What the Shell also leads on rating (5.0 vs 4.0) and ads (none vs shown). On price, ratings volume, in-app purchases and device support 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

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

What the Shell holds the better App Store score, 5.0 against 4.0. Both are backed by a comparable volume of ratings — 6 and 3 respectively. Written reviews point the same way: 100% of What the Shell's written reviews are positive against 0% of Zero21 Card Game's.

UpkeepUpdate frequency

What the Shell ships an update every 8 days, Zero21 Card Game every 65 months. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.

Scorecard5 real differences · 5 level
What the Shell versus Zero21 Card Game: the parameters behind the verdict, then further details
ParameterWhat the ShellZero21 Card Game
PriceFreeFree
Rating5.0 (6 ratings) — better4.0 (3 ratings)
Positive reviews100.0% of reviews — better0.0% of reviews
Number of ratings6 — better3
Update frequencyEvery 8 days — betterEvery 65 months
AdsNo — betterYes
In-app purchasesNoNo
MonetizationFree — betterAd-supported
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS16.015.6 — better
Further details — not scored
Size138 MB58 MB
Age rating4+4+
DeveloperChuck SmithLe Nhung

Customer experience

What the Shell

All ratings6 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews7 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Zero21 Card Game

All ratings3 ratings
Positive66.7%
Neutral33.3%
Negative0.0%
Written reviews1 reviews
Positive0.0%
Neutral100.0%
Negative0.0%

In-app purchases

None

What the Shell

No in-app purchases

None

Zero21 Card Game

No in-app purchases

Questions

Is What the Shell free?
What the Shell is free to download, with no in-app purchases.
Is Zero21 Card Game free?
Zero21 Card Game is free to download, with no in-app purchases.
Which has better reviews, What the Shell or Zero21 Card Game?
What the Shell is rated higher. What the Shell averages 5.0 out of 5 from 6 ratings, while Zero21 Card Game averages 4.0 from 3 ratings.
Do What the Shell or Zero21 Card Game have ads?
Zero21 Card Game shows ads; What the Shell does not.
Which is updated more often, What the Shell or Zero21 Card Game?
What the Shell ships an update every 8 days, and Zero21 Card Game every 65 months. Most recently, What the Shell was updated on November 1, 2026 and Zero21 Card Game on November 3, 2026.

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