I'm working on implementing a real-time monitoring system for our multiplayer game that needs to track metrics from potentially millions of concurrent players. We're looking at metrics like player actions, server health, network latency, and in-game economy transactions - all in real-time. The challenge is building an infrastructure that can ingest, process, and visualize this data with minimal delay while remaining cost-effective. We've considered tools like Kafka for event streaming, InfluxDB for time-series data, and Grafana for dashboards, but I'm curious about architectural patterns that have worked well at scale. What technologies and design patterns have you found most effective for real-time game monitoring? How do you handle data aggregation without losing critical granularity?