Design a PC Game Store, Entitlements, and Large-File Launcher Distribution

Design the backend for a PC game store and desktop launcher. Cover browsing and purchases, ownership entitlements, delivery of game builds and updates, and ownership verification before launch. Present the complete flow before deep-diving into content distribution and entitlements. ### Requirements and Scope Users are already authenticated. There are more than100 million registered users and10 million daily active users. Seasonal sales can increase browsing and checkout traffic50–100 times. A popular launch can require millions of users to download a50–100 GB build in a short window. Payment-provider internals, tax, the full social graph, chat, anti-cheat internals, and the game engine are outside scope. ### What a Strong Answer Covers Core entities and APIs across the full lifecycle, durable order-to-entitlement handoff, cached catalog reads, versioned manifests and CDN distribution, resumable verified downloads, launch authorization, and failure recovery. State an offline-launch policy rather than assuming one. ### Follow-up Questions - How do you prevent a successful purchase from being permanently missing from the user's library? - How would a launcher resume an interrupted100-GB download or recover from a corrupt chunk? - What happens when an entitlement is revoked after an offline token was issued?