Design a game leaderboard service

System Design: Game Leaderboard

Design a backend service that powers leaderboards for an online game.

Core functionality

• Players submit score updates (or score deltas) for a given game mode and season .
• Clients can query:
  • Top K players for a leaderboard (e.g., top 100)
  • A given player’s current rank and score
  • A range around a player (e.g., ranks 9,950–10,050)
• Support ties deterministically (e.g., same score → break ties by earliest timestamp or player_id).

Non-functional requirements (you may assume numbers)

• Large scale (e.g., tens of millions of players; up to hundreds of thousands of score updates/sec at peak).
• Low read latency (e.g., p95 < 100 ms for top-K queries).
• “Near real-time” freshness (e.g., leaderboard reflects updates within a few seconds).
• High availability across regions.

Constraints / discussion points

• Score update semantics: only allow monotonic increase (best score) vs allow arbitrary overwrites.
• How to handle seasons/resets , multiple regions , and multiple game modes .
• How to prevent/mitigate cheating and abusive update patterns.

Provide APIs, data/storage design, scaling strategy, and consistency tradeoffs.