Full-Stack Developer - Browser-Based Interactive Game Platform

Upwork Post: Full-Stack Developer Needed to Complete Browser-Based Interactive Game Platform We are looking for an experienced full-stack web developer to complete an existing interactive game platform and help convert the current work into a polished browser-based web application. The product is a synchronized, venue-based game experience where users join from their phones, make timed selections, view a shared game presentation, and compete on leaderboards. The final product should support both mobile player screens and large-screen venue/display screens, with all official game logic controlled by the backend. We are not looking for a real-time 3D action game or a Unity WebGL port. The ideal solution is a modern web app with a server-authoritative backend, lightweight real-time updates, persistent results, admin tools, rewards, achievements, and reliable reconnect/crash recovery. The existing project has a partial backend and a reference client build. The new developer should be comfortable reviewing the current implementation, reusing useful modules where appropriate, and rebuilding or refactoring areas that are incomplete or not production-ready. Main Scope of Work Web App Development Build or complete a browser-based application that includes: • Mobile user experience • Shared venue/display screen experience • Admin dashboard • User session/join flow • Timed game phases • Selection screens • Game progress display • Results screens • Leaderboards • Rewards and achievements screens Preferred frontend stack: • React • Next.js • TypeScript • Tailwind or similar UI framework We are open to other modern web stacks if the developer can clearly explain the advantages. Backend-Authoritative Game System The backend must be the source of truth. The client should not generate or submit official outcomes. Backend responsibilities include: • Session management • Server-controlled game phases • User selection validation • Game logic execution • Result generation • Stats generation • Leaderboard updates • Rewards • Achievements • Replay/reconstruction support • Crash and reconnect recovery The system must prevent duplicate runs, duplicate reward claims, and inconsistent user states. Scheduler and Synchronization The platform requires a reliable server-driven scheduler. Required behavior: • Server-side phase control • Strict phase gates for user actions • Shared timing across all users in the same session • Server timestamp synchronization • Support for browser refresh, phone sleep, disconnection, and reconnect • Ability for users to return to the correct phase after interruption • Durable state so incomplete or completed sessions do not lose key data Simulation / Rules Engine The game includes backend-generated outcomes based on user selections, configurable rules, modifiers, and stored inputs. The developer should be able to work with: • deterministic simulation • stored random seeds • configurable game rules • user selection validation • modifier/effect systems • event generation • stat generation • replayable outcomes The final system should produce structured result data that can support user screens, display screens, leaderboards, rewards, achievements, and admin review. Condensed Playback / Presentation Layer The platform includes a condensed playback or presentation layer that shows users what happened in the game in a short, engaging format. This should be driven by backend-generated events and should not invent outcomes on the client. The display should support: • key event highlights • progress updates • state changes • filler/narrative events when activity is low • simple visual overlays • timing-controlled presentation • animation hooks for future visual polish Animation Event Hooks The system should include a lightweight event-based animation trigger system, such as: PlayAnimation(EventType) Animations should be web-friendly overlays, not heavy video files or a Unity scene dependency. The goal is a fast-loading, reliable experience for mobile users and venue displays. Stats Integration The backend must produce structured statistics and result payloads that can be displayed in the frontend. Stats should be available for: • live progress screens • final results • leaderboard calculation • achievements • rewards • replay reconstruction • admin/debug review Rewards System The platform should support configurable rewards. Required features: • reward definitions • eligibility rules • reward timing rules • claim/redemption flow • duplicate-claim prevention • admin management • player-facing reward status Rewards should be based on backend-verified results only. Achievements System The platform should support achievements or milestones. Required features: • active achievements • completed achievements • claimable rewards • progress tracking • achievement history • rotating or configurable challenges • backend-verified completion logic Admin Tools The admin dashboard should support management and review of: • venues/accounts • sessions • schedules • users • game configuration • rewards • achievements • leaderboard results • system status • replay/debug data • support issues The admin experience should be usable by non-technical operators. Technical Requirements Strong candidates should have experience with: • React / Next.js • TypeScript • Backend API development • .NET / ASP.NET Core or Node.js • PostgreSQL • Entity Framework Core or similar ORM • SignalR, WebSockets, or Server-Sent Events • Real-time or synchronized web apps • Deterministic simulation or rules engines • Database design • Admin dashboards • Cloud deployment • Automated testing • Security and validation • Reconnect and crash recovery • API documentation Unity experience is helpful only for understanding the existing reference build. Unity should not be the primary production platform unless the developer can clearly justify that approach. Preferred Architecture The desired architecture is: Browser-based mobile user app Browser-based venue/display screen Admin web dashboard Backend API and rules engine PostgreSQL database Lightweight real-time event layer Cloud deployment The backend should control official state and outcomes. The frontend should display current state, collect user selections, show progress, and render presentation events. Known Areas Requiring Review The new developer should expect to review and resolve: • incomplete server-authoritative scheduling • mixed client/backend logic • local or mock fallback logic • incomplete result/stat payloads • incomplete presentation event feed • persistence gaps • duplicate-run prevention • duplicate-claim prevention • reconnect/crash recovery • cleanup of old or temporary code • API contract definition • staging/deployment setup • automated test coverage Expected Deliverables The final deliverable should include: • working browser-based user app • working venue/display screen • admin dashboard • server-controlled scheduler • backend-authoritative game logic • structured result and stats output • synchronized presentation/playback layer • rewards system • achievements system • persistent results • reconnect/crash recovery • clean API contracts • deployment-ready backend and frontend • documentation • test plan and QA checklist Ideal Candidate The ideal developer is a senior full-stack engineer who can own both architecture and implementation. They should be comfortable taking over an existing partial codebase, identifying what should be reused, refactoring what is incomplete, and delivering a production-ready web application. Please include examples of similar work, especially: • synchronized web apps • browser-based games or game-like systems • real-time dashboards • backend rules/simulation engines • admin portals • PostgreSQL-backed applications • reconnect/state recovery systems • rewards or achievement systems In your response, please briefly describe how you would approach reviewing the existing codebase and what you would prioritize first.