Dejan Zeljko

About Me Login

Sync Or Sink

Sync Or Sink Banner
Sync Or Sink on Steam

Game Overview

Sync Or Sink is a 2-player co-op Cold War submarine game about communication under pressure. One player is the Captain, confined to the cockpit—navigating by instruments, reading alarms, and guiding the mission. The other is the Engineer, moving through the submarine to diagnose and repair failures. A walkie-talkie style voice system (with custom high-pass/low-pass filters) forces clear, concise callouts as the Captain relays navigation and faults while the Engineer reports findings and fixes systems before time runs out.

In the 6-man strong team I served as the Lead Programmer and we published the game on Steam.

Gameplay Mechanics

Skills Demonstrated

Skill Description
Lead Programming Architected core systems, coordinated feature integration, and guided a 6-person team to a published release.
Networking (Steamworks) Lobby/session flow and state replication tailored for 2-player asymmetric co-op with integrated voice.
Audio DSP & UX Comms In-game walkie-talkie chain using custom HP/LP filters and VOX-style gating for clear radio-like comms.
Systems Design Station/instrument design for Captain; repair/task pipelines for Engineer; failure cascades and time-pressure loops.
Unity C# Development Modular subsystem components, event-driven faults, deterministic task logic, and robust input/interaction.

Game Features

Technical Concepts and Tools

Two-Player Architecture

Clear authority boundaries: cockpit-bound Captain UI/state and world-space Engineer interactions, synced for reliability.


Steamworks Networking

Stable 2-player sessions with voice; streamlined invites and reconnect handling for short, tense runs.


Audio Processing

Per-channel HP/LP filters, gain staging, and VOX to simulate radio bandwidth and cut through ambient noise.

Learning Takeaways

Designing strict role asymmetry taught the value of instrument-driven UI and spatial task design. The filtered VOIP system directly shaped teamwork quality, while fault cascades stress-tested replication, task orchestration, and recovery flows—key lessons for shipping a tight, communication-centric co-op experience.

Tools Used