Go Backend Developer (Slot Game Engine) - Freelance, Web

We're looking for an experienced Go Backend Developer to build a server-side slot game engine from scratch on a Go-based GDK. This is a 3-month freelance project with full ownership of the engine — from math model to RGS integration and certification readiness.

You'll be the game-logic authority on the project, working closely with a Game Designer, Mathematician, and Frontend Developer.

What you'll be doing

• Building the slot engine end-to-end: lifecycle interfaces (spin generation, keep-generate, history replay), win evaluation, and RGS integration contract
• Owning the game mathematics: RTP structure, reel strips, paylines / clusters / Megaways / avalanche, and probabilistic outcome modelling
• Implementing the full feature set: free spins, buy bonus, ante bet, max-win validation
• Externalizing all math configuration (reel sets, RTP, volatility, paytable) so Game Design and math can update values without code changes
• Running RTP simulation and validation harness; attaching simulation reports to each submission
• Driving builds through platform integration review and remediating findings until accepted
• Maintaining backend documentation: math/game-logic spec, config format, architecture records, README
• Actively using AI tools (Claude, ChatGPT, Gemini) to accelerate scaffolding, math modelling, and documentation — with reproducible, documented workflows

What we're looking for

• 3+ years of Go backend experience, layered service design, unit-testable game logic
• SDK lifecycle interfaces: spin, keep-generate, deterministic history replay
• Server-authoritative slot math: RTP, reel strips, paylines, Megaways, cascades, free spins, buy bonus
• All math in config — no hardcoded values; integer/fixed-point arithmetic only, no floating-point on monetary ops
• RNG exclusively via SDK-injected client
• Deterministic replay, idempotency, SDK compliance discipline, OWASP Top 10 awareness
• RTP simulation with reproducible reports; Go profiling, structured logging, clean SAST/DAST

Nice to have

• Production experience shipping slot or iGaming titles with server-authoritative math
• RGS or aggregator SDK integration experience
• Certification experience (GLI-19 or equivalent)
• Mathematics or probability background for RTP modelling
• gRPC alongside HTTP transport
• CI/CD pipeline experience
• TypeScript sufficient to read client-side SDK and reproduce frontend defects
• PixiJS / Spine familiarity

What we offer

• Strong mid-senior team — you'll work with experienced engineers, not learn on the job alone
• Real architectural influence — this is a greenfield engine, your decisions shape the product
• Flexible schedule — we care about results, not hours logged
• No micromanagement — you own your scope end-to-end and are trusted to deliver