What was the first multiplayer game you ever played on PC?

Who out there remembers the first game they ever played online, on their PC?

For me it was probably Diablo, or Shadow Warrior death matches. I still remember the modem sounds when my friend would try to connect to my game, and how surreal it felt playing against someone who wasn't sitting beside me with a controller in their hand.

What's everyone else's earliest memory of playing online for the first time, and which game?