- Input was laggy: Sometimes, keyboard and mouse input drops out. It will come back in about 10 seconds. I can confirm this is a bug with the game and is widely documented on the Steam forums. It is not present if you are using a controller. I tested (albeit briefly) with my Steam Controller and it worked fine. There are workarounds to try and fix this issue by modifying a configuration file for the game, but I have not tried these so I'm unsure if they work. The issue does seem to be less prevalent when running through Proton though, I read people saying it would happen very frequently for them. In my experience, it only happened about once every 20 minutes at most. Perhaps I just got lucky, but I played the game for quite a while and it wasn't as big of a deal as I read it was for some. Keep it in mind though, it's still present under Proton!
- Controller(s) not detected: Tested the game with a Steam Controller and it worked perfect - As long as you don't start the game from the launcher. If you do that, the game won't register any input from the controller. However, you can simply close the launcher after you configure the game from the launcher. Then, launch it normally and your Steam Controller will work. I suspect this is either a bug with how the Steam Controller works or how Proton handles switching from a launcher to a game and it can't correctly tell Danganronpa to use your Steam Controller as a controller and not a keyboard. Since you've set the game to use "gamepad" and the Steam Controller is a keyboard, it won't register input. Personally, the out-of-box Steam Controller configuration wasn't comfortably for me though