Catacomb Kids is a platformer roguelike in Early Access that looks like it is shaping up nicely, but I want to highlight this talk that Tyriq Plummer gave at GDC 2015, looking at how the map generator works. It is a useful look at some of the practical decisions that go into building a procedural map generator.
One thing that stood out to me is that the generator has the self-imposed constraint that the level is indestructible. Instead of using the approach of Spelunky, Minecraft, or Crypt of the Necrodancer, where the destructibility of the terrain lets the player edit the map to overcome limitations in the generator, Catacomb Kids deliberately operates in hard mode. Undoubtedly, this made it harder to develop, but combined with the other constraints it helps give the game its own unique feel.
Another thing that stood out was that adding simple spaces to give the player breathing room was important to the pacing of the level. A good generator usually has multiple textures, and sometimes adding a simple, empty room can give the rest of the complex space the context it needs.
The bit at the end about turning the quirks of the generator into features is the kind of thing that grabs me personally, because I’m a huge advocate for exploring the inner workings of algorithms. Design is a conversation between the designer, the machine, and the player. Seeing the odd outcomes repurposed for new mechanics is exactly what can happen when you really engage with what the machine is telling you.