I had a coworker like that once. The trouble is that no-one but him could maintain it. So, after he already left for another project (within the same company),

I had a coworker like that once. The trouble is that no-one but him could maintain it. So, after he already left for another project (within the same company), the managers called him back in to continue adding features to it. In my view, it would have been better to just spend time to refactor, until anybody in the team would be able to understand it. That episode reinforced the belief in me that KISS is the best approach in writing code. I try not to write "smart" code but simple, easy to understand, so I can go on vacation or change projects without being constantly dragged into the same codebase.