Design a digital game distribution platform. Cover the game catalog and user library, purchases and refunds, promotions, authentication and entitlements, large downloads, patch delivery, and the operational controls needed to release updates safely. ### Constraints & Assumptions - Game binaries and patches are large, while catalog and entitlement records are transactional. - A user may install on several devices and may be offline temporarily. - Promotions can create sharp traffic spikes. - Refund and entitlement changes must not be lost or applied twice. ### Clarifying Questions to Ask - Which devices and regions are supported, and is offline play required? - Are publishers allowed to stage regional releases and roll back a bad patch? - What refund rules and payment providers are in scope? ### What a Strong Answer Covers - Separated catalog, pricing, order, entitlement, library, build, and download responsibilities. - An idempotent purchase and refund workflow with an auditable entitlement ledger. - Immutable manifests, chunked content-addressed storage, CDN delivery, differential patches, and integrity verification. - Promotion caching without treating cached price as checkout authority. - Device authentication, offline licenses, release canaries, rollback, capacity planning, and observability. ### Follow-up Questions - How would you prevent a partially downloaded patch from corrupting an installation? - What happens when a refund races with an offline launch? - How would you roll back a patch after only one region has received it?