• Lead Pongz (multiplayer Mahjong, 7-engineer team) — 41K registered / ~3.4K daily active players across Android and iOS. Own the server and API architecture end to end
• Scaled the game server horizontally from a single instance — Redis pub/sub fan-out, leader election over a shared global queue (fixing matchmaking split-brain), distributed locking, and failover that hands live games to peer nodes on drain with zero session loss
• Architected socket framework — enforced connection state machine, typed event dispatch, TTL-expiring offline message queue, parallel-probe connectivity with adaptive polling
• Designed server-authoritative protocol resolving race conditions from latency and message reordering — monotonic turn sequencing, fingerprint-based deduplication on reconnect, exponential-backoff with jitter
• Built three-stage AFK system — warning → server-tracked idle → bot substitution mid-match. Full state resync on player return without interrupting remaining three
• Engineered hierarchical state controller — 8 phases, 14+ substates — replacing boolean flags with typed queries as single source of truth for gameplay, UI, networking
• Extracted 8 reusable Unity systems (Event Bus, State Machine, Save, Pause, Logging, UI, Loading, Popup) — split event/message bus, WeakReference lifecycle, atomic-write persistence, bit-flag pause — adopted team-wide
• Grew the test suite to 3,332 passing tests with CI-enforced coverage floors (80% lines / 85% functions)
• Led 7 engineers — architecture, code reviews, sprint planning across client, server, and API

• Shipped endless runner — 5M+ downloads, 4.6 stars on Google Play. Improved engagement 30% via player-data-driven iteration
• Introduced TDD team-wide — ratings improved 1.5 stars. Authored 25-chapter technical course on game architecture
• Built procedural generation tools — 40% faster level design. Optimized rendering — 25% higher FPS on low-end devices
• Mentored 3 junior developers — technical reviews, pair programming, coding standards

Unity hot reload — domain reload 3–5s → 7ms. Two paths: Roslyn debug (90% of edits), MonoMod detours (structural changes).

Custom 2D engine, C++/SFML — impulse solver with warm starting, Baumgarte correction, semi-implicit Euler, fixed timestep, spiral-of-death prevention, 3 collision algorithms, 8 materials, hand-written vector math, 3-tier AI.

Open-source Unity UI framework (MIT) — CRTP builders, Roslyn codegen with partial classes, bidirectional O(1) lookups, 8-tab editor. Full documentation site.

Hardware-integrated archery — Unity, Arduino, projector, OpenCV. Real-time arrow impact detection.