Comparison

Zero/Sum vs Only One

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

Head to head
About

Zero/Sum

Solve mathematical puzzles to uncover a cure for cancer in this unique puzzle game. Experience an 80s action movie-inspired storyline with live-action cinematics and a variety of fresh puzzle mechanics. Features daily challenges and time trials.

Highlights
  • Unique and original puzzle gameplay
  • 80s action movie-inspired storyline
  • Full motion video cinematics with real actors
  • Variety of puzzle types (melting, number)
  • Daily Challenge Mode with new puzzles
  • Time Trial mode
Features
Read full description

On the eve of discovering a mathematical cure for cancer, your mentor, Professor Claire Liddy, is murdered. Fortunately, before she died, the Professor was able to erase many of the plus and minus signs with her bloody hands, saving the cure from falling into the hands of her killers. Now it is up to you to fill back in the missing parts of the equation and resolve your professor's cure. It's up to you to cure cancer -- AGAIN! (It's a comedy). FEATURES - A completely UNIQUE and ORIGINAL puzzle game! - Puzzle gameplay that will make you feel and look SMART! - A thrilling, 80s ACTION MOVIE-inspired storyline! - Full motion video GREEN SCREEN cinematics! With REAL human ACTORS! - NO mention of CANDY or CUPCAKES or sweets of any kind in the story at all! - A variety of different puzzle types and mechanics to keep things FRESH (melting puzzles, number puzzles, and so much more)! - A Daily Challenge Mode featuring 10 NEW puzzles EVERY DAY! - Time Trial mode - try to beat your best time on RANDOM PUZZLES! - Completely INDEPENDENTLY developed and published! (Support your local punk band)! I ignored my newborn child to make this game, please ignore yours to play it!* *Note: I worked on the game every night after my son fell asleep, there is nothing more important to me than being a father. That being said, this game is a CLOSE second. Like neck and neck, really.

About

Only One

This is a minimalist logic puzzle game where each level requires you to find a unique solution related to the number one. Explore diverse puzzles and receive hints if you get stuck for over 45 seconds.

Highlights
  • Minimalist logic puzzles
  • Unique solutions per level
  • Theme based on the number one
  • Variety of fun puzzles
  • In-game hints after 45 seconds
Features
Read full description

Let there be one! Only One is a minimal logic puzzle game where each level has it's own logic to be solved. Every level's solution has to do with something related to the number 1. One color? One piece? or even the number one itself. Just let it be one. Explore a variety of fun puzzles. And if in any case you get stuck on a level after 45 seconds a hint icon would be available to provide you with some help. Can you make it Only One?

Screenshots

Zero/Sum4 screens
Only One4 screens

Verdict

The call

The clearest difference is review sentiment: Only One at 100% against Zero/Sum's 54%. Only One also leads on rating (5.0 vs 4.2). Zero/Sum's advantage is price (Free vs $0.99) and update cadence (every 2 months vs every 39 months). On ads, 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

Zero/Sum is free to download; Only One costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Only One holds the better App Store score, 5.0 against 4.2. That said, the two scores are not equally well evidenced: Zero/Sum has 27 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 54% of Zero/Sum's written reviews are positive against 100% of Only One's.

UpkeepUpdate frequency

Zero/Sum ships an update every 2 months, Only One every 39 months. The most recent releases landed on October 26, 2026 and October 24, 2026 respectively.

Scorecard7 real differences · 3 level
Zero/Sum versus Only One: the parameters behind the verdict, then further details
ParameterZero/SumOnly One
PriceFree — better$0.99
Rating4.2 (27 ratings)5.0 (2 ratings) — better
Positive reviews53.8% of reviews100.0% of reviews — better
Number of ratings27 — better2
Update frequencyEvery 2 months — betterEvery 39 months
AdsNoNo
In-app purchasesNoNo
MonetizationFree — betterPaid
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS8.0 — better15.6
Further details — not scored
Size973 MB65 MB
Age rating12+4+
DeveloperSean KearneyKofi Austin

Customer experience

Zero/Sum

All ratings27 ratings
Positive77.8%
Neutral7.4%
Negative14.8%
Written reviews13 reviews
Positive53.8%
Neutral23.1%
Negative23.1%

Only One

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Zero/Sum

No in-app purchases

None

Only One

No in-app purchases

Questions

Is Zero/Sum free?
Zero/Sum is free to download, with no in-app purchases.
Is Only One free?
Only One costs $0.99, with no in-app purchases.
Which has better reviews, Zero/Sum or Only One?
Only One is rated higher. Zero/Sum averages 4.2 out of 5 from 27 ratings, while Only One averages 5.0 from 2 ratings.
Do Zero/Sum or Only One have ads?
Neither Zero/Sum nor Only One shows ads.
Which is updated more often, Zero/Sum or Only One?
Zero/Sum ships an update every 2 months, and Only One every 39 months. Most recently, Zero/Sum was updated on October 26, 2026 and Only One on October 24, 2026.

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