System Design Arcade vs Don't Break Prod

NEW: THE AI ARCADE. Eight games on the system design round that didn't exist three years ago: RAG, LLM serving, embeddings, guardrails, and GPU fleets. Free, no subscription, and it plays offline. The system design interview is the one where the whiteboard goes blank. You've read the books. You've watched the videos. But when the interviewer says "design Instagram," or now "design a retrieval system for our support bot," you freeze, because reading about consistent hashing at 2am is not the same as knowing it cold. System Design Arcade is the fix. It turns every building block into 60-second arcade levels you can actually finish. On the subway. In line for coffee. While waiting for CI. On a plane with no Wi-Fi. THE AI ARCADE AI engineering is its own interview round now, and most prep hasn't caught up. The AI Arcade drills the systems behind it: - Design a RAG System: chunk boundaries, hybrid retrieval, reranking, and the permission bug that ends careers - LLM Serving: batching, KV caches, streaming, and GPU memory as the binding constraint - Feed Ranking: retrieval, ranking, and the feedback loop that decides what a model can ever learn - Embeddings: what "similar" means, how many dimensions you need, and migrating models without silent breakage - Feature Stores: one definition, two readers, and point-in-time correctness between training and serving - ML Observability: catching a model that is wrong while every dashboard stays green - AI Guardrails: where the checks sit, prompt injection from untrusted text, and what a model is allowed to reach - GPU Infrastructure: memory, interconnect, scheduling, and the bill FIVE TRACKS, ONE CURRICULUM Concept Arcade: master one building block at a time. Caches, databases, queues, replication, sharding, load balancing. Problem Arcade: design complete systems end to end. URL Shortener, Rate Limiter, News Feed, Chat, Ride Sharing, and a new Key-Value Store. The classics, played out like boss fights. Tool Arcade: hands-on drills with the infrastructure you'll use on the job. Redis. Kafka. Docker. Kubernetes. And Vector Vault, the vector store behind semantic search. AI Arcade: the eight games above. Story Mode: narrative capstones that walk an onsite round end to end: a Twitter-style home timeline, a chat system, Dropbox, typeahead search, a rate limiter, and a URL shortener. CHALLENGE TYPES THAT DON'T FEEL LIKE FLASHCARDS Multiple choice, ordering puzzles, fill-in-the-blank, API Builder, Architecture Builder, and Scenario-Why drills. Each level mixes formats so your brain has to actually engage. The Scenario-Why drills train the reasoning behind the answer, not just the answer. REVIEW THAT SPACES ITSELF OUT Miss a challenge and it comes back in Power-Up Review. Clear it and it returns on a widening schedule, so what you learn stays learned. DAILY CHALLENGE A fresh challenge every day, the same one for you and your study buddy. Streak counter. Optional reminder notifications, opt in from Settings. BUILT FOR YOUR EYES Retro arcade aesthetic by default. Pixel fonts. Neon glow. Prefer something softer? Switch to the playful sticker-card vibe, or open the Theme Lab and tune background, glow, gradient, and font until it feels right. Read Aloud narrates every explanation, so you can learn while you walk. YOUR PROGRESS STAYS YOURS Start playing instantly: Level 1 of every game needs no account. A free sign-in with Apple, Google, GitHub, or email unlocks every level and backs up your progress across your iPhone and iPad. Progress saves on your device. We use product analytics to see which levels need work, never the content of your answers. FREE TO PLAY No ads. No paywalls. No subscription. Every level is free with a free account. New games ship every sprint. Start with Level 1.

Don't Break Prod turns system design practice into a daily habit. Every day brings one timed incident: a production system is failing, the clock is running, and you make the calls to bring it back. Diagnose the root cause, mitigate, recover, and harden before the timer hits zero. It is built for engineers preparing for system design and on-call interviews, and for anyone who wants to think more clearly about how real systems break. THE DAILY INCIDENT A new production failure every day, the same one for everyone. A cache that went cold, a queue that will not drain, a cert that expired at midnight, a cache key that leaked one tenant's data into another. Time is short, wrong moves cost you seconds, and your score is the time you have left. One scored run per day. Share your result as a spoiler-free card and compare calls with your team. PRACTICE THAT STICKS Work through core topics at your own pace: caching, load balancing, message queues, databases, sharding, consistency, rate limiting, CDNs, and full design walkthroughs like URL shorteners, chat, and news feeds. Spaced repetition brings back what you are about to forget, right when you need it. THREE WAYS TO ANSWER Multiple choice, fill in the blank, and drag-to-order questions, each written to test whether you understand the tradeoff, not whether you can recognize a term. KEEP YOUR STREAK Show up daily and build a streak of days without breaking prod. Earn failover freezes that quietly cover a missed day. Your whole history lives in Profile as a day-by-day grid: every incident survived, every failover spent, every day the pager won. Compare your all-time score with other players on the Game Center leaderboard. PRIVATE BY DESIGN No account, no sign-up, no tracking, no ads. Everything you do stays on your device. The leaderboard is optional and runs on Apple's Game Center. Every question is original writing. The concepts are standard system design material, explained plainly, so you leave understanding the why, not just the answer.