Using this assignment to investigate Doom modding has made me really want to make my own WAD. The only thing I know about what I want to make right now is a movement-focused mod that would enable the player to traverse environments in new and interesting ways.

Maybe use something like the Adhesion Gel that was cut from Portal 2 before its release? https://theportalwiki.com/wiki/Adhesion_Gel

Or maybe a grappling hook, like Bionic Commando had?