The mapper nightfall has posted screenshots and information about his latest projectg Volatile which is currently in progress. Volatile is a 15-20 map pack for ZDoom with maps that have very non-linear layouts and focuses on adventure rather than spamming thousands of revenants at you, though it will also fall sideways to dropkick beneath your belt when you least expect it to. There'll be quite heavy use of ZDoom features, including custom monsters and probably weapons (when he gets around to doing that) though nightfall hopes to put in some compatibility mechanism so that you can still play it with mods. The project has basically existed for eternities (since 2011) according to the mapper under an infinite number of names. Let's hope he gets it finished this time as it looks very promising.