Gumdrop Grid: Candy Puzzle Game for iPhone
A candy puzzle where gummies melt and the board cascades, taken from concept through App Review with AI as the build team
At a glance
I acted as design lead and executive sponsor for Gumdrop Grid, a candy puzzle game for iPhone where matching gummies melt and the board drops into cascades. I researched the market, designed the game, brand and business model, answered App Review with a redesign, ran the go-to-market campaign, and used Claude (AI) to help build the app and its playable prototype.
The challenge
Prove that one product leader, with AI as the build team, can take a consumer game from an idea through App Review, with real monetization, privacy and launch planning, and stand apart in one of the most crowded categories on mobile.
What I led
- Researched the category: Block Blast’s ad-only model, player complaints about ads and where themed puzzles win
- Set the concept: a sweet candy puzzle with collectible characters and daily reasons to return
- Answered Apple’s 4.3(a) rejection by redesigning the core: melts, gravity cascades, a 30-level campaign and Pal powers
- Designed the levels, obstacles (jelly, caramel, sour drops) and the star and reward system
- Directed the candy brand, Gummy Pals and the App Store art
- Designed a layout that adapts to every iPhone shape, including folding iPhone Duo
- Built the business model: gem packs, Sugar Pass subscription, US-only launch and posted odds
- Ran go-to-market: teaser, launch and engagement posts, stories, a share image and a 20-second promo video
- Built a playable prototype from the real game, with a guided tour
- Wrote the store listing, privacy policy, release notes and App Review replies
The outcome
Apple rejected the first build under Guideline 4.3(a) as too similar to other block puzzles. I redesigned the core around melts, cascades, a 30-level campaign and Pal powers, and resubmitted the same day, November 13, 2026. It is waiting for review and will be released manually once approved.
Overview
Gumdrop Grid is a candy puzzle game for iPhone. Players fit gummy pieces onto an 8×8 board, melt five or more same-color gummies from different pieces, and watch the board drop into cascades across a 30-level campaign. Apple first rejected 1.0 under Guideline 4.3(a) as too similar to other block puzzles, so I redesigned the core and resubmitted it on November 13, 2026.
How I led it: I acted as design lead and executive sponsor, running it as a one-person product studio. I set the vision, researched the market, designed the game, the brand and the business model, answered App Review with a redesign, ran the go-to-market campaign, and used Claude (AI) to help build the app and its playable prototype.
What’s in the game:
Core rules: line clears plus melts, with gravity that sets off cascades
Campaign: 30 levels in Gumdrop Gardens, Caramel Canyon and Sour Swamp, each with goals, a move limit and up to three stars
Obstacles: jelly, caramel that never falls and sour drops that spread
Pal powers: 10 collectible Gummy Pals (common, rare and secret, with posted odds), each with its own board power
Extras: Sugar Rush endless mode, Bomb, Shuffle and Undo, daily treats, haptics and fully offline play
Services
Customer & Market Research, Product Concept, Game & UX Design, Art Direction, Monetization & Pricing, Interactive Prototyping, AI-Assisted Development, Go-to-Market & App Store Launch
Client name
Gumdrop Grid (independent product by John Karl)
Team
John Karl, Design Lead & Executive Sponsor
Prototype
Market research
User research
UX Decision
Go-to-market
This is a working prototype. Follow the guided steps or switch tabs and use the controls. Everything responds live.
Market research
Goal:
Find a place to win in one of the biggest, most crowded categories on mobile.
Block Blast: the category leader, the No. 1 most downloaded mobile game worldwide in Q1 2026, earning from ads alone with no in-app purchases
Kids and families: the leading block game carries a 17+ App Store rating, leaving room for a sweet, all-ages puzzle
Category analysis: classic block puzzles are saturated, while themed games with collections and boosters earn more per download
App Review: Apple rejected the first build under Guideline 4.3(a) as too close to existing block puzzles. The lesson: in a saturated category a theme alone doesn’t set you apart; the rules have to
User research
Goal:
Ground every decision in real input from the people who use it, and say plainly what still needs validating.
Voice of the customer: players’ top complaint about the leaders is excessive ads interrupting play, and some say they would pay for a better ad experience
Proto-personas (hypotheses): the five-minute break player, the streak collector and the parent who wants a game a kid can play too
Research plan: a TestFlight beta, day-1 and day-7 retention, combo and booster use, and a short survey on ads versus paid options
Why Each UX Decision Was Made
Goal:
Every level should feel quick and fair, and the rules should be the game’s own, not a reskin of the category leader.
Rules, not just art: Apple’s 4.3 rejection showed a candy theme isn’t enough, so color now matters (melts) and the board drops (cascades)
Goals and moves over endless score: levels give short, clear wins and a reason to come back; endless mode stays for score chasers
Obstacles that teach: each world adds one new idea (jelly, then caramel, then spreading sour drops), so difficulty grows without a manual
Characters that do something: every Pal has a power, so collecting changes how you play, not just how the board looks
No ads at launch: the biggest complaint about the category leader, so 1.0 earns through optional gem packs and a subscription
Posted odds and fair rescues: capsule odds are shown in the game, and Bomb, Shuffle, Undo or extra moves turn a stuck board into a decision
Every iPhone shape: the board resizes live for standard iPhones, iPhone Duo open and closed, landscape and Split View
Privacy as a feature: Data Not Collected, rated 9+, and fully offline play
Go-to-Market as Part of the Build
Goal:
Launch with a clear business model and a campaign ready on day one, not as an afterthought.
Business model: free to download in the United States, five gem packs from $0.99 to $19.99 and a $4.99 Sugar Pass subscription
Store listing: “Melt gummies, drop cascades”, rated 9+, with Data Not Collected and a live privacy policy
Campaign: moves from tease (“Something sweet is coming”) to launch (“Out now on iPhone”), with melt and cascade, Gummy Pals and “Beat my score” posts, plus stories
Video: a 20-second vertical promo for Reels, TikTok and Shorts showing melts, cascades, levels and Pal powers
Roadmap: optional rewarded ads and a No Ads purchase in 1.1, then more worlds and online duels with Game Center
Gumdrop Grid from concept to App Review: prototype, iOS build, redesign, go-to-market campaign.
Final observations
Gumdrop Grid shows how a product executive carries a consumer product from research to launch, and responds when a platform pushes back. When Apple judged the first build too close to existing block puzzles, I didn’t argue about the art; I changed the rules: melts, cascades, a level campaign and Pal powers. AI helped turn those decisions into a new build the same day. Next steps are App Review, the release, TestFlight learnings and day-7 retention, then 1.1.
John Karl
19 Years • Product & UX Design Leader Leading Mobile Product for 500K+ Users
If you like what you see or have any questions, feel free to send me an email anytime.
Selected work
[2010 -2025]
