Hold the Prod: Tower Defense

“Why didn’t you put up a Firewall right away?” “What’s your retry policy for the AA gun?” “Please draw one more box.” This is a modern system design interview at Big Tech. While the interviewer asks questions, drones and missiles are heading for the Uptimeville datacenter. Place defenses around your datacenters, move them mid-battle and hold the SLA. Let one hit through, and clients can’t use your services. Your units: Alert, Rate limiter, Packet loss, Cache, Load balancer, kill -9 and Observability, plus a Firewall net dropped right onto the datacenter. Cache works as a decoy, kill -9 burns through a whole swarm, and without Observability you can’t see the saboteurs. Before some waves you’re offered an event: Friday release, Budget freeze or P0 incident. It gets harder, but it pays more. In endless mode the interview ends with a grade: from Intern (“Thanks, we’ll get back to you.”) to Principal (“Now you run these interviews yourself.”). • Campaign: 15 levels on five maps, stars for SLA • Level challenges with medals • Endless mode and Load • Daily shift: the same one for everyone, with a streak • 18 achievements and a leaderboard in Game Center