Hello everyone. Just wanted to provide an update.
First, I'm almost done with the procedural system to generate rooms and place objects.
I decided to switch to toon shading but also added GI (that can be turned off).
Third, I optimized a lot by parallelizing more logic.
The game still isn't exactly lightweight due to the amount of physics, physics-related logic, the size of the maps, AI and more, but I'm making sure I get at least 30FPS on my laptop (which, coincidentally, has the closest commercial CPU to the one of the Steam Deck).
Now I'm focusing on refining graphics and adding content/tuning the gameplay.
Here are a few screenshots.