What is it?HammUEr is a (currently Windows only) plugin that lets you build your levels with Valve's Hammer Source map editor (VMF), Doom3's DoomEdit (MAP/PROC) or a Quake-based map editor like Radiant, Jackhammer or Trenchbroom (MAP). With just a few simple clicks, you can have them imported into your Unreal Engine project as a collection of meshes placed in your scene the way you want, where you want. Want to change something? Make your edits in your favourite tool, then save, re-import, and you're done.
During the importing process you can assign materials already in your project to the original material names, or if you have the source images - (TGA/BMP/PNG/JPG)/VTF&VMT/MTR(D3)/SHADER(Q3)/WAD(Quake1 & Halflife)/WAL(Quake 2) - you can import them into UE as material instances based on a template material of your choice, and let HammUEr automatically find and assign the right ones. Don't want certain materials to show? Mark them no-draw and HammUEr will automatically not build polygons for them!
Want to start building a level in Hammer with your UE materials for true WYSIWYG level editing? HammUEr can do that by exporting your UE material textures to VMT/VTF combos for easy use in Hammer with one click.
Have Source models you created for your maps? HammUEr can bring them into Unreal Engine for you and places them where they belong.
Use overlays and decals? HammUEr will also import those for you.
I'm not even close to done adding features, so stay tuned.
Where do I buy it?
Go to itch.io
But what about the Marketplace?
Epic has decided not to carry the plugin for various reasons beyond my control.
for the latest news.
With thanks to @JoeWintergreen for the video and screenshots.