ZDoom

Sounds solid, will keep an eye on github and notifications from this post

This is already high on the list - once the initial slate of bugs has been reduced.

Technically it shouldn't be too hard when using the same method as GZDoom uses for rendering portals, i.e. render the sky polygons as stencil and fill it in later when the scene is complete.

The way GZDoom does skies out of the standard assets in the IWADs is quite nice and hasn't made me look for skyboxes or some kind of alternative.

Is something similar a possible consideration in Polymost?