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Design a Digital Game Distribution Platform

OpenAISoftware Engineer · Technical Screen
HardSoftware EngineerTechnical ScreenSystem Design

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Design a high-scale game distribution platform covering reliable payment and entitlement tracking, content-addressed binary chunk distribution, offline license leasing, and canary rollouts.

Scenario

Design the backend infrastructure for a global digital PC game distribution platform (similar to Steam or Epic Games Store). The platform must handle high-stakes transactions, massive binary payload distribution, offline play, and rapid developer deployment workflows.

Requirements

Functional Requirements

  • Commerce & Entitlements: Users can purchase games, receive immediate access, and request refunds (which revokes entitlements transactionally).
  • Build Ingestion & Patching: Developers upload new game versions (20 GB – 150 GB). The system splits builds into content-addressed chunks, deduplicates data across versions, and generates delta manifests.
  • Content Delivery: Clients download, resume, and verify builds using manifests and cryptographic hashes.
  • Licensing & Offline Play: Clients can launch and play games offline for up to 30 days via cryptographically signed local machine leases.
  • Release Management: Support phased/canary deployments (e.g., 5% -> 25% -> 100%) and instant rollbacks.

Non-Functional Requirements

  • Scale: 150 million registered users, 15 million concurrent connected clients, and 5 million simultaneous downloads during major release spikes.
  • Consistency: Strict consistency for purchases, refunds, and entitlement state. Eventual consistency is acceptable for catalog views and download analytics.
  • Integrity: Zero tolerance for corrupted binary chunks during download or disk assembly.
  • Bandwidth Efficiency: Minimize CDN egress by downloading only mutated chunks between game versions.

What to Cover

  1. High-Level Architecture: Diagram the flow between client, storefront/entitlement services, build ingestion pipeline, and delivery edge.
  2. Build Chunking & Storage: How large binaries are chunked, deduplicated, and organized in object storage.
  3. Client Download & Patch Protocol: Manifest schema, chunk integrity validation (e.g., Merkle trees), and resumability.
  4. Licensing & Offline DRM: Mechanics of generating, verifying, and renewing machine-bound cryptographic leases.
  5. Deployment & Rollback Strategy: Canary rollout routing and cache invalidation strategies during instant rollbacks.

Hints

Hint 1

Separate metadata and manifest delivery from raw binary chunk delivery so chunk storage remains entirely immutable and CDN-cacheable.

Hint 2

Use content-defined chunking (such as FastCDC) and Merkle trees to produce deterministic chunk IDs that maximize deduplication across versions.

Hint 3

For offline licensing, issue asymmetric-key signed tokens bound to client hardware fingerprints with an embedded expiration lease.

Follow-up questions

  • How would you integrate local peer-to-peer (P2P) transfer between clients on the same local subnet to reduce external CDN egress?
  • How does your CDN cache-invalidation and origin-shield architecture protect origin storage from a thundering herd during a global midnight launch?
  • If a critical zero-day security flaw is found in a game binary currently in a 10% canary, describe the precise steps to halt rollouts and force client repair.