How to better organize the architecture of a chess service (like Chess.com) for Russia with 1 million users and 50k DAU, where a player plays 5 games a day, with profiles, matchmaking, and achievements?

For a chess service with 1 million users and 50k DAU, where a player plays about 5 games a day, the architecture should be built considering scalability, fault tolerance, and low latency.

Main components:

• Frontend — web and mobile clients.
• API Gateway — request routing, authentication.
• Profile Service — storing user information (relational database, e.g., PostgreSQL).
• Matchmaking — service that matches opponents based on rating and activity. Can be implemented using queues and caching (Redis).
• Game Service — managing game state, moves, timing. For storing game state, fast databases (e.g., Redis for current games) and long-term storage in a relational database can be used.
• Achievements and Statistics — a separate service with analytics capabilities.
• Notification System — push notifications, email.

Technologies and approaches:

• Use microservice architecture for independent component scaling.
• Horizontal scaling of game services and matchmaking.
• Caching frequently requested data (profiles, ratings) in Redis.
• Use WebSocket or gRPC for real-time in games.
• Store logs and statistics in analytical databases (e.g., ClickHouse).

An example of a simplified architecture:

[Frontend] <-> [API Gateway] <-> [Profile Service (PostgreSQL)]
                                |-> [Matchmaking Service (Redis + Go)]
                                |-> [Game Service (Redis + PostgreSQL)]
                                |-> [Achievements Service]
                                |-> [Notification Service]

This approach will ensure scalability and responsiveness of the service under high load.