Last Epoch, which recently had a major update. I've been flatly unable to get it running in two different operating systems now, and haven't even bothered to try tinkering with it for the last two days. It even mocks me with a Platinum rating on protondb...but all the reviews on Ubuntu are at least 9 months old and that was back when the game had a native Linux version. My biggest worry is that the latest patch has broken something for Ubuntu, but what's most likely is that my configs are just borked in a unique way that I'm too stupid to fix.