So, something kept filling up my disk space. I finally decided to run drive usage analytics to find a output_log.txt file sized at whopping 21gb. It apparently was produced by Unity. I don't really know Unity, so I don't know how to find the source game. The path is AppData\LocalLow\DefaultCompany\Game Jam SEP-01-2018\output_log.txt. Is there a way to find which game to blame?

Also, a reminder that this can happen. Be careful.