DoNotTouch.java

It's Black Friday, and your inventory service is in the line of fire. Normally you'd just rewrite it, but this is the sacred legacy service the CEO authored himself. Refactoring it is seppuku for your career. It's synchronous, it's untouchable, and the write storm is already here. The Job: Keep the write load from overwhelming the service you're not allowed to change, so orders keep landing and latency stays sane. Protect the masterpiece and your job.

Free to play, no account needed. A deterministic engine grades your design against this scenario's SLA - error rate, latency, and cost.