System designHardsd-g265

Subject Real time systemsLevel Senior–Staff~50 minCommon in Security · Distributed systems interviewsIndustries Computer games, Technology

Question

Design the real-time state-synchronization layer for a 60-player battle-royale game. Each match runs ~25 minutes; players send inputs at 60 Hz and need to see other players' positions, projectiles, and hit events with <100 ms perceived lag despite 30–150 ms RTT. The server must be authoritative (anti-cheat), and clients on flaky mobile connections must degrade gracefully. How do you keep all 60 clients consistent at scale across thousands of concurrent matches?

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.