Ask HN: Have you ever been on a project where the key person was hit by a bus?

We talk about the "bus count" all the time, but I haven't heard a first-person account of what actually happens if one of a team's key people dies or rage quits or otherwise is unavailable. Have you ever been a part of such a team? How did it occur and more importantly how did the team bounce back? Did you successfully take over their code or does nobody touch it?