Jin Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Jin Kang (강진형)

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

Development through release and live operation

Unity / C# game developer. Over four years of fully remote work with Voodoo, Amanotes, Homa Games, BoomHits by BoomBit, and Lion Studios, I developed and delivered 30+ mobile games.

As development lead and sole programmer of a three-person team, I owned gameplay implementation, test builds, SDK integration, 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 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 operation. So I account for review and operational issues during development, reducing rework later.

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

Owning development and release in a three-person team

  • Publisher 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.
  • I coordinated schedules and feedback directly with the publishers’ product, QA, and business teams.

Remote work in English with teams in four countries

Worked over Slack with teams in France, Vietnam, Poland, and the United States. I handled test build handoff, QA response, and scheduling directly in English throughout the four-year engagements.

Korean and East Asian market context

I can review Korean localization for nuance and cultural reference. For K-Games 3D, I watched the Korean series Squid Game early in Korea and pitched the game adaptation before it spread worldwide; it recorded a CPI of $0.03 in BoomHits’ UA testing. I wrote the 6~8 hour script of a commercial game in Korean, and I build and run the i18n and LLM translation pipeline of a multilingual service.

sayneinteractive@gmail.comdevelopersayne.dev  |  github.com/kangbba
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Jin Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Demolding 3D

Homa Games | Development Lead · Sole Programmer
3-person teamMobile F2P2M+ 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 2M+ downloads.

What I owned

  • Development lead and sole programmer of a three-person team with a technical artist and a designer.
  • Everything on the client outside technical art: gameplay, UI, data structures, SDK and platform integration, builds, and store submission.
  • Sole owner of 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 tuning it into something that holds up 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 keeps physics running for nothing, 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 Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

K-Games 3D

BoomHits by BoomBit | Development Lead · Sole 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 owned

  • 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.

Rate increase and UA test result

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 owned test design and metric interpretation. I turned the results they shared into implementation work and kept a cycle of folding them into the next build.

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

30+ mobile games developed & delivered

Contracts with publishers in France · Vietnam · Poland · United States (2019 ~ 2022)
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 · Laundry Master · Small Business Sort · Island Escape · Computer Art 3D · Eyebrows Art 3D · Tuft a Rug · Draw & Clean · Organize Your Stuff · Hexa World

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.

That is where I learned that retention does not save a title if CPI does not follow. From then on I understood the metrics the publisher was reading before building, and making development decisions against numbers became normal.

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, fully remote 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 held the contracts and the daily communication with publisher CEOs and business managers.

Development cycle

I completed and submitted a new title for publisher CPI and A/B testing every 2~3 weeks. Titles with strong metrics moved into further development and live operation. 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 Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Lion Studios: selected projects

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 rather than staying inside the programmer role I 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.
  • Because the crush sequence does not depend on runtime physics, it keeps the realism of the simulation while staying precisely controllable for balance.
Gameplay videoyoutu.be/ek0wLSIAe-A

Blade Master 3D

Mobile F2P · rendering feedback
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 adding blade types costs no extra work.
  • 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.
Gameplay videoyoutu.be/wKtdx7YR3js
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Jin Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Lion Studios: selected projects

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 Kang   (강진형) · SayneSenior Unity 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 Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

The Secret of Greenwood Isle

Recent independent work | Solo development | Steam · South Korea's STOVE | Released Jan 2026
Unity / C#Multiple 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 is a different class of problem from hypercasual. 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 owned that from design through commercial release.

Systems I built

  • Managing 6~8 hours of branching script as text did not hold up, 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 Kang   (강진형) · SayneSenior Unity 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 spinning the slot recruits seven hero types: 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 Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Modu Dining

Recent independent work | Solo development · operation | 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 reads a single menu photo and extracts items, prices, and option structures into a digital menu. Translation is part of the same pass.
  • Menu names and prices go through an admin review step, and low-volume work is handled directly rather than through the API to keep call costs down.
  • Built an owner-facing menu and QR management console so restaurants can update content during operation.

How it runs

  • The initial build is done, and owners manage menus and QR codes from an admin console themselves. 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 operating load does not grow with each new location.

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Jin Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Other personal projects

Real-time translation device

Contract hardware delivery · 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 notify, scan, and connection on Streams, disposing StreamSubscriptions explicitly to manage connection lifecycle.

ESP32 firmware · LCD output

  • Wrote ESP-IDF / ESP-ADF firmware, connecting asynchronous state across both the app and device.
  • Hand-built and integrated a Korean bitmap font so translated Korean text could be rendered on the LCD.
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Jin Kang   (강진형) · SayneSenior Unity 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 repeatedly against publisher UA schedules and feedback.
  • Set up event, funnel, and KPI dashboards, and turned the CPI, retention, and A/B results the publisher interpreted into implementation work 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.
  • Cutting repeat 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, did the 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 (instrument · monitor · fold into builds)
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 Kang   (강진형) · SayneSenior Unity Game Developer  |  developersayne.dev

Engineering outside games

Server, database, web, and embedded work, and what it gave back to 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, designing call cost and the review step alongside it.
  • 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 notify, scan, and connection on Streams, disposing StreamSubscriptions explicitly to manage lifecycle.
  • Wrote ESP-IDF / ESP-ADF firmware, implementing the async flow between device and app from both sides.

What this gave back to 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 done art-tool work, UA metric response, and business admin like contracts and invoicing. That makes working with marketing and business teams straightforward, not just with 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
Overseas publisher contracts: development lead · sole programmer. 30+ mobile games developed and delivered while on leave from university.
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.com  |  developersayne.dev  |  github.com/kangbba
Seoul, South Korea · Open to remote work · willing to relocate
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Resume
Jin Kang - Portfolio — Jin Hyung KANG