First week of work behind me, I've done some very crude procedural generation but i'm extremely happy with the layouts I'm getting as the output.

The goal is to have lots of levels which are well interconnected both vertically and horizontally. 

Assets are placed using bitmasking and some python scripts to generate the meshes in blender. This way I can just say what kind of a tile should be placed(Room, Stair, Corridor), and the rules will automatically choose were walls should be etc. with barely any performance hit no matter the size.  
  
The biggest struggle was finding a system which will work well with godots GridMap as I felt like I'm not willing to rewrite loading in octants, generating multimesh instances for an arbitrary number of assets etc. so I decided I'm going to adapt to the very restricted set of functions that GridMap offers. Hence my approach and plan is generating a ton of combined assets in blender, we'll see how far that will take me :)

Next step is making rooms which are 2 levels high, and add balconies to them.

If anyone cares, the meat of the game will be noita style "Wand Crafting" except that wands are guns with some classic arena style shooter combat. I already have a simple implementation of the "wand building" mechanic which is based on the command pattern, so even at this early stage i can make both hitscan and projectile shots follow arced paths, bounce, multicast, stack modifiers etc.

I think a roguelite combined with arena shooter style action is basically my wet dream, so wish me perseverance.

Low-key happy with laying the groundwork for procedural generation.