UMAPINFO allows several source ports to describe meta-data associated with levels (such as their name, music, sky texture, secret exit, etc.) It supported by PrBoom+, DSDA-Doom, GZDoom, Eternity Engine (devbuilds), Woof, Doom Retro (partially), and possibly more (let me know). It was developed in 2017 but saw little use. So I made a little collection of UMAPINFO/Dehacked files for classic WADs.   Intermission screens and episode selection for Ancient Aliens, Eviternity, Valiant: