basic shadowplay-like functionality with nvenc.
The script is only barebones right now.
Point INSTALL (line 5) to your ffmpeg executable (built with nvenc support).
Change -s 2560x1440 (line 9) to your resolution. (X11 resolution, not the resolution the game is being run at).
Default save time is 3 minutes, change it on line 13.
./gloom.sh
Press q in the terminal to save the last 3 minutes.
That's it. Videos are saved in ~/Videos/
When recording for a really long time you might have problems saving, because ffmpeg then has to cut a very large video down to the time.
Honestly this is a pretty significant issue and you probably want to use ShadowRePlay-Linux instead, which seems to resolve the issue and also handles non-nvidia gpus!