Writing game server code is hard. Based on my experiences writing the server code for battle.net and Guild Wars, I'll talk about the challenges and pitfalls you're likely to encounter as you write the code for your next online game. I'll discuss how to build reliable game services that are resistant to hacking. I'll talk about how to make your customers happy by handling common failure conditions that many games seem to ignore to their detriment. And I'll share ideas on building distributed systems that can recover from problems without requiring human intervention so customers do not quit in anger. Join me for a whirlwind tour of writing the code for an online game service.