System Design Arcade vs Word Wipeout

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.

Word Wipeout makes learning songs and phrases irresistibly fun for children. Simply pick a song from the library or paste any song lyrics or phrases and tap the Sing musical note button — the words appear in large, easy-to-read text perfect for little learners. When your child is ready for a challenge, tap the Eraser button and watch Pac-Man, Shark, Tornado, or several other animation characters come to life, chomping through 25% of the words with sound and animation. Keep tapping to erase 25% more words progressively — each round a little harder than the last — until your child is singing from memory all on their own. How It Works: • Pick a song from the built-in library or type or paste any song lyrics or any phrase you want to memorize • Tap the Sing musical note button to display the words in large text • Practice memorizing the words, with all of the words displayed • Tap Erase to let Pac-Man or other animations wipe out 25% of the words • See if you can remember the words that were wiped out • Keep Erasing — each round erases 25% more, building memory • Hit the 'Full Screen' button to operate in full screen. • Tap Reset to bring all the words back and start again • Tap Settings to change font since or change the erase animation character to a Shark, Tornado, and several others (or None). Selecting more than one animation will randomly pick from those selected. • Load a new song or phrase anytime with New Song Built for Learning: Word Wipeout uses a proven memory technique — gradual word removal — that turns rote memorization into an engaging game. Children build reading fluency, phrase recall, and confidence without even realizing they're learning. Perfect For: • Primary school children learning songs or phrases for class or church • Parents and teachers who want a simple, screen-time-worthy tool • Though targeted to children and teachers, this app is great for anyone learning to memorize a song or phrase. If you are too old to enjoy the animation, just turn it off. No cost. No ads. No in-app purchases. No hidden fees. Just pure free learning.