Question How to build a level ?

Hi, I have this problem.
I'm trying to build a level, doom-style, but I don't know how to do it.

I tryed making walls prefabs, but Unity is giving me problems with prefabs (and also I don't think that's the right solution).

I'd like a simple tool, like DoomBuilder, but don't know any.
Also ... this is the main problem: i noticed that when I use a material on objects, tiling and offsetting is buond to the material and not the object (which is really dumb, if you ask me).

Is there a way to bind offset and tile to the object instead ?

 

That's a perfectly legit way to build a level, but it's not the only way. You could also use a 3D modelling app like Blender. You could use Unity's ProBuilder plugin (Which is like a 3D modeling app except you can use it in editor). There are CSG-style plugins like SabreCSG or Realtime CSG. There are other third-party plugins that take a different, more-generative approach like Archimatix or Tessera. You can use a combination of these techniques too.
Check out here for plugins:
https://assetstore.unity.com/?category=tools/level-design&orderBy=1

The way a texture is mapped over a mesh is usually determined by a mesh's UV coordinates. There is no way to edit these in the basic Unity editor, so you'll need to use a plugin like ProBuilder or an App like Blender if you want to modify these.