Anyway to get the budgie login window to list other windows managers,

I have a game that is taxing my graphics card a little to much, and I don’t want to overclock, so I installed a lighter windows manager called fluxbox so it doesn’t compete with the game for any resources. The trouble is that whatever login manager Budgie uses doesn’t list this Windows Manager as an option, when I boot up. I looked at the settings and I am not seeing anything to enable this.

Hi there - we use LightDM as the displaymanager/login.

When you installed fluxbox does it provide a valid desktop file in /usr/share/xsessions/?

To get this working, you would need to figure out how fluxbox and lighdm work together.