Olimpijski Kviz — Milano-Cortina 2026

A real-time interactive quiz platform built for the Milano-Cortina 2026 Winter Olympics. Every evening during the Games (Feb 6–21), TV Slovenia 2 broadcast a QR code and up to 25,000 viewers joined a live quiz on their phones — answering 16 timed questions about Olympic history, Slovenian athletes, and winter sports trivia, competing for a trip to the LA 2028 Summer Olympics.

16 daily quizzes. 15 seconds per question. Time-based scoring. Live leaderboards. All synchronized without WebSockets.

• Keep 25,000 concurrent mobile users in sync during a live TV quiz with sub-second accuracy
• Handle answer submissions idempotently under unreliable mobile connections (double-taps, retries, network drops)
• Deliver a smooth, real-time experience using server-side rendering only — no WebSockets, no client-side JS framework
• Integrate sponsor video ads mid-quiz without breaking the flow
• Go from zero to production in ~4 weeks

A poll-based state synchronization architecture: HTMX morph-swaps poll the server every 1–2 seconds, and a Redis-cached quiz state machine drives phase transitions automatically via BullMQ workers.

State machine with 6 phases manages each quiz: LOBBY → QUESTION → SPONSOR_EXPOSITION → WAITING → STANDINGS → COMPLETED

Caching layer with 95%+ Redis hit rate eliminates database pressure — leaderboard queries reduced from ~25,000 to 1 per question round (25,000× improvement). TTL jitter prevents cache stampedes.

Idempotent submissions via Prisma transactions prevent double-counting. Distributed Redis locks prevent race conditions during phase transitions.

• Fastify v5 + TypeScript — SSR with fluent-html + HTMX + Tailwind
• PostgreSQL + Prisma — 13 models, connection pooling (6 per process)
• Redis — quiz state cache, leaderboard cache, distributed locks, pub/sub
• BullMQ — phase advancement worker (1s tick), leaderboard aggregation, email delivery
• PM2 — multi-process clustering across 3–6 × 8vCPU servers
• Prometheus + Grafana + Loki — real-time monitoring and alerting
• Cloudflare — DDoS protection, CDN, R2 file storage

1. TV broadcasts QR code → viewer scans → lands in Lobby
2. Quiz starts → Question phase (15 sec timer, time-based scoring 50–100 pts)
3. Optional Sponsor Exposition (full-screen video ad)
4. Waiting phase (answers locked, suspense builds)
5. Standings revealed (live leaderboard, 10 sec)
6. Repeat 16× → Completed → final rankings

Aggregate leaderboard: "Best 10 of 16" scoring — must complete 10+ quizzes to appear in final standings.

• Grand prize: Trip for 2 to LA 2028 Summer Olympics (flights, hotel, tickets)
• Runner-up: Peak brand Milano-Cortina 2026 Olympic winter jackets
• Daily draws: VIP Planica ski jumping tickets, Ford Explorer test drives, Peak hoodies

• Mid-quiz video ads: Full-screen sponsor exposition between question rounds
• Result page overlays: Video ads with frequency capping (sessionStorage-based cooldown)
• Random fallback: If no quiz-specific sponsor, random sponsor video plays
• Sponsors reach thousands of engaged, non-skippable viewers at peak attention moments

Load tested with k6 on local MacBook Pro M1 (4,000 VUs):

• 1,066,605 total requests — zero failures
• 2,959 req/sec sustained throughput
• 108 ms median response time
• 98.4% of requests under 1 second
• 18% latency improvement between test iterations (Jan 12 → Jan 16)