Home Run — two families, one house, thirty attacks. Defend it with system design.
Mira and Aarav met in a college lecture and, four years later, moved into their first house together. Neither family approves. Her side, the Kapoors, and his, the Sharmas, set out to break the house until the two of them give up and come home. Every attack lands on one part of the house and is one system design idea, with one question and four answers. The right answer repairs what was hit. The wrong one and the damage stays: you are told why that answer would not hold, and the same attack comes again with its answers shuffled.
Play Home Run →Free, and no account needed — play as a guest. Runs in the browser — nothing to install.
Seven relatives — a retired colonel, a brother with 300 online friends, a gossiping aunt, a mother who is only helping, an electrician uncle, a cousin who thinks he is a hacker, and a sweet, unstoppable grandmother — come at the house ten times an act.
| Act | Attacks | What it covers |
|---|---|---|
| Moving Day | 1–10 | one relative at a time on the obvious weak spots: single points of failure, authentication, rate limiting, authorization, queues, caching, secrets, choosing a database, backups, load balancing |
| The Families Get Serious | 11–20 | scale and data: workers, autoscaling, consistency, encryption, object storage, CDNs, indexes, monitoring, idempotency, a cache in front of the database |
| The Alliance | 21–30 | two of them at once: failover, API gateways, transactions and locking, backpressure, secrets management, disaster recovery, circuit breakers, sharding, tracing — and the housewarming, where all seven come together |
Chacha cutting the power on move-in night is a single point of failure. Rocky getting 300 friends to ring the doorbell at once is rate limiting. Dadi ordering the same sweets twice is idempotency. The idea is named once the attack is repaired, with a sentence or two on why it works.
| Level | What it asks |
|---|---|
| Beginner | What is the idea? Name the fix. |
| Intermediate | Which trade-off? Pick the better fix. |
| Advanced | Design it to hold at scale. |
Each level is the same thirty attacks with different questions about each — two per attack, 180 in all, every one a real system design question. Get one wrong and the mission fails; the retry asks the other question on the same idea. Finishing a level means playing the story again and being asked harder things.
System design is hard to learn from a list, because every idea in it is an answer to a particular kind of trouble. Here the trouble comes first — the power goes, the doorbell floods, two people edit the grocery list at once — and the idea is what fixes it. There is no timer and there are no lives: the only cost of a wrong answer is facing that attack again, and you are told why your pick fails but not what the right one is, so the second attempt has to be worked out rather than remembered.
Start on Beginner. It asks what each idea is and names the fix, and needs no more than having used the web. Intermediate and Advanced assume you have built or run something.
No. The attacks come in order, and each one opens the next. Any attack already defended can be faced again; replaying it changes nothing.
The damage stays, you are told why that answer would not hold, and the same attack comes back with its four answers shuffled. Nothing is lost.
Yes. Every game on SULULU is free and there is nothing to buy.