I am in the early planning stages of my next and possibly final Wolfenstein 3D mod. It will be called "The Black Gate" and the story will be centered around preventing the Nazis from opening a portal to hell. Hitler believes he can harness the armies of hell in order to win the war and has commissioned the building of a device to open a "Black Gate" deep in the catacombs beneath the castle. However, this experiment goes very wrong and opening the Black Gate results in hordes of demons flooding into Earth, killing at will.
It will feature 10 or 12 128x128 levels. As usual for my mods, it will start off with a mapping style similar to that of the original Wolfenstein 3D and Spear of Destiny levels, with the addition of the new enemies featured in Atomprojekt. Around 3/4 through the mod, the portal will be opened and the final few levels will be multi-layered, with the player having to travel back and forth between earth and hell in order to complete the levels. The hell dimension will be a completely different from earth with new enemies, statics, keys, etc to go with it. The final level will involve destroying the device and closing the gate permanently.
As of now, since this is still in early stages, I am aiming for late 2017 or early 2018 for release.