Adding the FOV calculation wasn't too different to the Python version, though I did run into the minor issue of where to update the FOV state on the tile map. The place I initially thought would be good was when rendering, but then I realised that this would require the render_map method to take the map mutably. While that would work, it doesn't feel right that a function for rendering should need to mutate the map.

I eventually settled on putting the tile update in the update_fov function. It would make it more expensive to run, given it's now got to iterate the tile map, but the map isn't huge and the function only gets called on a map or player position update.

I decided to implement the scrolling map. The maps are a little boring for it, but at least it demonstrates a method. It took an embarrassingly long time to figure out why the scroll clamping was weird on the bottom and right edges of the map. I had the signs flipped in the clamp function...

I've adjusted the room generation to use the map size to calculate the maximum number of rooms. That way the density of each level will be roughly the same.