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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Jin Hyung Kang (강진형)

Developer handle: Sayne
Unity Game Developer
Gameplay Systems | Prototype to Store Release | Remote Publisher Collaboration

From Development to Release and Live Operations

Four years of remote work with Voodoo · Amanotes · Homa Games · BoomHits · Lion Studios, delivering 30+ mobile games.

Development lead and sole programmer of a three-person team, from gameplay implementation to store submission and QA follow-up.

I worked as a full-time client-side game developer at Supercent, a Korean mobile game studio.

Separately, I self-published a solo-developed game on Steam and South Korea's STOVE game platform as an independent project.

I currently build and operate Modu Dining, a multilingual QR menu service used by restaurants in South Korea.

I have taken a product through the entire cycle several times: concept, implementation, store submission, post-release support, and live operations. So I can see review and operational issues coming while still in development, and save that time.

30+
mobile games developed & delivered
5
publishers, all outside Korea
approx. 2M
downloads, top title
$0.03
lowest CPI
104%
crowdfunding, solo title

Development and Release in a Three-Person Team

Projects ran with one developer (me), one technical artist, and one designer. As development lead and sole programmer I handled Unity / C# development, SDK integration, test and store builds, and QA response.

Remote work in English with teams in four countries

Four years of remote collaboration over Slack with teams in France, Vietnam, Poland, and the United States. I handled build deliveries, QA follow-up, and scheduling directly in English.

Korean and East Asian market context

I can review Korean localization for nuance and cultural references. For K-Games 3D I saw Squid Game early in Korea and pitched the adaptation before the show spread worldwide.

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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Demolding 3D

Homa Games | Game Programmer
3-person teamMobile F2Papprox. 2M downloadsRuntime mesh deformation

What it is

A 3D simulation game about making your own resin mold. You place stickers, pour resin, add glitter, let it cure, then peel the mold off. Released by Homa Games, with about 2M downloads.

What I handled

  • Development lead and sole programmer of a three-person team with a technical artist and a designer.
  • All client-side work outside technical art: gameplay, UI, data structures, SDK and platform integration, builds, and store submission.
  • I handled day-to-day communication with the publisher: test build handoff, scheduling, and QA follow-up.

Engineering decisions

The de-molding interaction uses runtime mesh deformation. The real work was making it work reliably on mobile.

The opening mold drop is a code-driven curve rather than a physics simulation: it keeps the bounce feel and plays out identically every time. Peeled pieces carry colliders baked in advance and left disabled until the moment they fall. With that many pieces, leaving them enabled incurs continuous, unnecessary physics cost, and creating them at drop time concentrates the cost in a single frame; pre-baking and disabling avoids both. Sticker placement is validated with Physics.ComputePenetration.

Gameplay videoDemolding 3Dyoutu.be/afdvvXj0Gvw ↗
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

K-Games 3D

BoomHits by BoomBit | Game Programmer
3-person teamMobile F2PCPI of $0.03UA-driven iteration

What it is

A 3D mobile game inspired by the Korean series Squid Game. I watched the series early on Netflix in Korea and pitched turning it into a game before it spread worldwide.

I implemented the concept within a tight window and submitted it to BoomHits’ UA testing. The project ran from ideation through implementation.

What I handled

  • Development lead and sole programmer of a three-person team, from gameplay systems to the store submission build.
  • Test submission, scheduling, QA follow-up, and coordination with the publisher’s team.
  • Iterated builds on UA test results and publisher feedback.

Contract Rate Increase and UA Results

Trusting how consistently and professionally I had handled the earlier titles, BoomHits raised my contract rate without my asking.

It performed well enough in BoomHits’ user acquisition testing to record a CPI of $0.03, with a BoomHits executive calling it “an unbelievable number.”

How it was validated

The publisher led test design and metric interpretation. I repeated a cycle of turning the shared results into implementation tasks for the next build.

Gameplay videoK-Games 3Dyoutu.be/nxdweZOK4zA ↗
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

30+ mobile games developed & delivered

Publisher contracts in France · Vietnam · Poland · United States, followed by a full-time role in South Korea (2019 ~ 2024)
Voodoo logo
VoodooFrance4 titles
Tap X 2 · Roll Down Bowling · Secret Shadow · RushHour Dash
Amanotes logo
AmanotesVietnam2 titles
Music Roller · Slope Bowling
Homa Games logo
Homa GamesFrance4 titles
Demolding 3D · Dancing Star · Rescue Dash · Dig & Mix
BoomHits by BoomBit logo
BoomHits by BoomBitPoland6 titles
K-Games 3D · Animal Clash · Dip & Sell · Dr. Syringe · Doll House DIY · Creature Rush
Lion Studios (AppLovin) logo
Lion Studios (AppLovin)United States15 titles
Press'em All · Blade Master 3D · Iconic Makeup 3D · Couple Rope 3D · Hat Designer · Airport Luggage Control and 9 more
Supercent logo
SupercentKoreaFull-time
2023 ~ 2024 · first place in the in-house game contest

How it started

In 2018, in the early days of hypercasual, Voodoo reached out first after seeing games I had released on my own. Roll Down Bowling, one of the early titles, hit 42% D1 retention, but acquisition cost did not work out in the publisher’s UA testing and it never scaled.

Five publisher contracts over four years

Voodoo, then Amanotes, Homa Games, BoomHits by BoomBit, and Lion Studios: five publisher contracts over four years. I managed schedules and QA follow-up directly while working fully remotely throughout.

The team

We were a three-person team: one developer, one technical artist, one designer, and I led it. Art and visuals were theirs. I was the only developer, and I also handled contracts and day-to-day communication with publisher CEOs and business managers.

Development cycle

I completed and submitted a new title for publisher CPI and A/B testing every two to three weeks. Titles with strong metrics moved into further development and live operations. To match that pace I consolidated movement, scaling, ad flow, animation, scroll views, and game managers into shared systems, cutting the time spent rebuilding them per project.

All titles were developed and delivered under publisher contracts; some were developed under the names RevoluApps and Studio Aroka.

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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Projects built with Lion Studios

From ideation driven by TikTok trend research through gameplay implementation

Press'em All

Crush simulation · Blender → Unity
Press'em All game screen 1Press'em All game screen 2Press'em All game screen 3
  • The team had no pipeline for deformation effects, so I stepped beyond my programming role, learned Blender, and built the physics simulation myself.
  • Modifier-driven deformation does not survive an FBX export, so I baked the simulation into shape keys and exported it into a Unity prefab.
  • The press's lowest point and the model's highest point over time are baked into the prefab in advance, and the relationship between the two is what defines 'pressing' in code.
  • Because the crush sequence does not depend on runtime physics, it preserved the realism of the simulation while allowing precise tuning for balance.
Gameplay videoyoutu.be/ek0wLSIAe-A ↗

Blade Master 3D

Mobile F2P · visual effects
Blade Master 3D game screen 1Blade Master 3D game screen 2Blade Master 3D game screen 3
  • Applied post-processing and emissive materials to the core loop of heating and hammering blades at the forge, expressing the light and heat of hot metal.
  • Built a laser phase that cuts automatically along the model’s outline. Drop in a new model and the cut path follows, so new blade models required no additional cut-path setup.
  • Aiming for the satisfaction of the grinding itself, I tied surface wear and the heated metal slowly cooling to grinding progress. Effect intensity and rendering cost stayed inside the mobile F2P performance budget.
  • That feel does not come from the screen alone, so I synchronized haptic feedback with the interaction: a sustained rumble while grinding and a short pulse when a stage completes, so players could tell by touch what was happening.
Gameplay videoyoutu.be/wKtdx7YR3js ↗
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Projects built with Lion Studios

From ideation driven by TikTok trend research through gameplay implementation

Iconic Makeup 3D

Bézier geometry · asset baking
Iconic Makeup 3D game screen 1Iconic Makeup 3D game screen 2
  • Coordinated shading and presentation with the technical artist so makeup and facial detail read in close-up.
  • Generated eyebrow geometry from Bézier curves and built a baking workflow that turns the result into reusable assets.
  • Documented the generation and baking steps so the artist could use them for repeat work.
Gameplay videoyoutu.be/4ZV5hpoo0hA ↗

Couple Rope 3D

Shared rope mechanic · level integration
Couple Rope 3D game screen 1Couple Rope 3D game screen 2
  • Implemented movement and interaction for two characters tied together, and integrated it into the levels.
  • The pair share one rope, so moving one pulls the other. I used that constraint as the puzzle, tuning obstacle placement and rope length per level.
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Other titles built and delivered

16 more beyond the featured work | Delivered as publisher UA tests and store builds
Video collectionyoutu.be/ZsC5ofbSpGc ↗
Animal Clash game screen

Animal Clash

BoomHitsyoutu.be/zgMu93WbrI0 ↗
Dip & Sell game screen

Dip & Sell

BoomHits
Dr. Syringe game screen

Dr. Syringe

BoomHits
Doll House DIY game screen

Doll House DIY

BoomHits
Creature Rush game screen

Creature Rush

BoomHits
Hat Designer game screen

Hat Designer

Lion Studios
Airport Luggage Control game screen

Airport Luggage Control

Lion Studiosyoutu.be/b23_2fj0oGk ↗
Laundry Master game screen

Laundry Master

Lion Studios
Small Business Sort game screen

Small Business Sort

Lion Studios
Island Escape game screen

Island Escape

Lion Studios
Computer Art 3D game screen

Computer Art 3D

Lion Studios
Eyebrows Art 3D game screen

Eyebrows Art 3D

Lion Studios
Tuft a Rug game screen

Tuft a Rug

Lion Studios
Draw & Clean game screen

Draw & Clean

Lion Studios
Organize Your Stuff game screen

Organize Your Stuff

Lion Studios
Hexa World game screen

Hexa World

Lion Studios
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

The Secret of Greenwood Isle

Recent independent work | Solo development | Steam · South Korea's STOVE | Released Jan 2026
Unity / C#Mystery visual novel6~8 hours of playtimeMultiple endings · puzzlesReleased on Steam · STOVE104% crowdfunded
Steam store page and in-game screens | dialogue · exploration · branching choices
Steam store pageTrailer · screenshotsstore.steampowered.com/app/3790450 ↗

What it is

A mystery visual novel set in a remote island village. You gather clues through conversation and exploration, combine items to solve puzzles, and the story and ending shift with the player’s choices and values.

This required a different kind of problem-solving than hypercasual work. The work is keeping six to eight hours of story coherent alongside the choice flags, items, and save state that accumulate across it, and I handled that from design through commercial release.

Systems I built

  • Plain text became impractical for managing six to eight hours of branching narrative, so I built a node-based script editor as a Unity Editor extension. Dialogue and choices are composed as nodes, and the whole flow is managed visually.
  • Nodes carry conditional gates that branch on accumulated flags and value state. Reachable endings and orphaned branches are traceable in the editor, so the structure stayed under control as routes multiplied.
  • Multiple routes and endings, exploration and interaction, items, escape-room puzzles, save and load, multi-resolution UI scaling, and build setup for Steam and South Korea's STOVE game platform.

Solo from concept to release

  • Scenario writing and game design, Unity / C# development, UI, asset integration, sound editing, and store submission.
  • With no art or sound staff, I produced the backgrounds, animation, SFX, and BGM myself. Backgrounds were generated with MidJourney, animation with Niji Journey, and SFX and BGM samples with ElevenLabs, then all hand-edited and reviewed before integration. That combination is what made a commercial-length solo release possible.
  • Reached 104% of the crowdfunding goal on South Korean crowdfunding platform Tumblbug, and followed through to merch production and backer shipping.
store.steampowered.com · store.onstove.com · tumblbug.com
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Hell Keeper

Released Oct 2025 | 3-person team | Unity / C# development | South Korea’s ONE store · WebGL
Unity / C#Casual slot defenseReleased on ONE storeWebGL port

What it is

A casual defense game where players spin a slot machine to recruit seven types of heroes: water, fire, ice, lightning, poison, rock, and elemental. You upgrade and merge them into a lineup, choose the timing of each upgrade, and stop incoming waves to clear stages.

Data and content pipeline

  • Separated hero, buff, and augment data into ScriptableObjects with a runtime loading structure.
  • Built an Editor pipeline that imports balance data from Google Sheets into Unity assets, so tuning numbers does not require code changes.
  • Built an Editor tool that batch-generates augment assets, reducing repetitive work when adding content.

Release and WebGL port

After its official release on South Korean app marketplace ONE store, I ported it to WebGL. The browser build preserves the mobile gameplay loop and data structure while making the game playable without installation.

Core gameplay loop

Spin → recruit heroes → upgrade and merge → build a lineup → defend waves → advance through stages

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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Modu Dining

Recent independent work | Solo Development · Operations | Multilingual QR menu service
Next.js / TypeScriptLive in productionMultilingual i18nUsed by restaurants in South Korea
The service in production | theme selection and language switching | modudining.com

What it is

A multilingual QR menu service for restaurants. Diners scan a code and read the menu in their own language; owners manage menu content and QR images themselves.

What I build and run

  • Next.js / TypeScript frontend, database and storage, i18n, deployment, and incident response.
  • A pipeline built on the Claude API that extracts items, prices, and option structures from a single menu photo and converts them into a digital menu. Translation runs through the same pipeline.
  • Menu names and prices go through an admin review step, and low-volume tasks are handled directly rather than through the API to control call costs.
  • Built an owner-facing menu and QR management console for live updates.

How it runs

  • The initial build is done, and owners manage menus and QR codes directly through an admin console. Day-to-day operation does not need a developer on hand.
Open the serviceLive production sitewww.modudining.com ↗

Designed to remain maintainable after setup

Restaurants manage their own menus and QR codes, so operational workload does not grow with each new location.

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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Other personal projects

Real-time translation device

Hardware Project Delivered for a Client · Flutter + ESP32

End-to-end flow implemented

Device triggerBLESTTTranslationTTSDevice reply

Flutter app · BLE communication

  • Connected a Flutter app to an ESP32 device over BLE, implementing the async path from device input through delivery of the translated response.
  • Handled BLE notifications, scanning, and connections with Dart Streams, disposing StreamSubscriptions explicitly to manage connection lifecycle.

ESP32 firmware · LCD output

  • Wrote ESP-IDF / ESP-ADF firmware, coordinating asynchronous state between the app and the device.
  • Hand-built and integrated a Korean bitmap font so translated Korean text could be rendered on the LCD.
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Systems behind shipping

F2P instrumentation and build iteration, reusable structure, technical art collaboration

F2P monetization · UA instrumentation

  • Implemented IronSource mediation and ad flow, and integrated GameAnalytics, Firebase Analytics, Facebook SDK, and Crashlytics.
  • Submitted test builds iteratively based on publisher UA schedules and feedback.
  • Set up event, funnel, and KPI dashboards, then turned the publisher’s analysis of CPI, retention, and A/B test results into implementation tasks for the next build.

Reusable production systems

  • Consolidated movement and scaling components, ad flow, animation management, custom scroll views, and game managers, bundling them with frequently used utilities and shared assets for reuse across projects.
  • Reducing repeated implementation shortened the initial development time for new titles.
  • Editor code and Google Sheets integration kept map generation, balance values, and data asset creation structured and manageable.
  • Data is separated into ScriptableObjects with a runtime loading structure.

Technical art collaboration

  • Aligned on URP / Shader Graph workflows with the technical artist to keep visual iteration moving.
  • Where needed, I handled the required art-tool work myself, including Blender simulation and geometry generation, and integrated it into the Unity build.

Game stack

Analytics
GameAnalytics, Firebase Analytics, Crashlytics, Facebook SDK
Monetization
IronSource mediation, ad SDK integration, UA testing
Metrics
CPI, retention, A/B tests, funnels, KPI dashboards (instrumentation · monitoring · build iteration)
Architecture
OOP, abstraction, ScriptableObject-driven data, reusable gameplay / UI systems, event-driven patterns
Unity
UniTask, UniRx · reactive patterns, DOTween, Built-in RP, URP, Profiler
Rendering
Built-in RP, URP, pre-Shader Graph shader code, batching, draw call reduction, lightmaps, post-processing
Platforms
Steamworks, Steam, South Korea's STOVE PC game platform, App Store Connect, Google Play Console, South Korean app marketplace ONE store
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Jin Hyung Kang   (강진형) · SayneUnity Game Developer |  developersayne.dev

Engineering outside games

Server, database, web, and embedded work, and how it carried over into game development

Web · running a live service

  • Next.js / TypeScript frontend with database and storage, i18n, deployed and operated on Vercel.
  • Built a Claude API pipeline that extracts menu structure from a single image, with API cost and review built into the workflow.
  • Real users mean I own incident response and data integrity. It is the same work as post-release support on a game.

Mobile · embedded

  • Used Dart’s null safety and nullable types to surface BLE connection and scan failure paths in the type system.
  • Handled BLE notifications, scanning, and connections with Dart Streams, disposing StreamSubscriptions explicitly to manage lifecycle.
  • Wrote ESP-IDF / ESP-ADF firmware, implementing the async flow between device and app from both sides.

How this experience carried over into game development

Flutter’s Stream-based async carried over into UniRx and reactive patterns in Unity, and composing screens from nested widgets became the node-assembled script structure in The Secret of Greenwood Isle.

Handling servers, databases, and deployment myself gave me a working understanding of the architecture beyond the game client.

I have handled art-tool work, responding to UA metrics, and business administration, including contracts and invoicing. This experience helps me communicate smoothly with marketing and business teams, as well as technical artists and designers.

Stack

Web
Next.js, TypeScript, Supabase, Vercel, i18n, LLM pipelines, deployment and operations
Mobile
Flutter / Dart null safety, nullable types, Stream / listener, BLE
Embedded
ESP32, ESP-IDF / ESP-ADF, backed by an EE degree

Experience · Education · Military service

2014 ~ 2016
Republic of Korea Army, honorable discharge as Sergeant (during university, ~21 months)
2018
미세먼지 숨: first Android air-quality app, released as a student in South Korea, ~5K downloads with no marketing. Tongue Keeper: Top Excellence Award, Korea's 5th ICT Smart Device Contest.
2019 ~ 2022
Contracts with five overseas publishers (France · Vietnam · Poland · United States): Voodoo · Amanotes · Homa Games · BoomHits · Lion Studios. Development lead and sole programmer of a three-person team, delivering 30+ mobile games. I took leave from university and worked on this full time for four years.
2022 ~ 2023
B.S. in Electronic Engineering, Kookmin University, Seoul, South Korea (Aug 2023)
2023 ~ 2024
Supercent: full-time client developer. 1st place, in-house game competition.
2025 ~ 2026
The Secret of Greenwood Isle: solo development, released on Steam and South Korea's STOVE game platform.
2026 ~ now
Modu Dining: multilingual QR menu service, solo development · operation.
Contact   sayneinteractive@gmail.comdevelopersayne.dev ↗github.com/kangbba ↗
Seoul, South Korea
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Resume
Jin Hyung Kang - Portfolio — Jin Hyung KANG