Lol, there are a few ways that you can achieve doors, however it will require modification of the wall detection loop since you need to allow for the fact that doors are 'half-way' in a wall (or offset by half a wall etc) and sometimes reinstate a ray if needed (like when its opening).

That said, its not on the plan yet, but something to think about.

On a side note here's the raycaster I am talking about:



Unfortunately OTBP website is gone and I couldn't find any topic about it here, so I had an hard time finding the image.

Actually I think looking up and down simply involves moving the screen content up and down in the screen, with no extra 3D calculations. It's kinda like in Duke Nukem 3D (the original version, not remakes nor the hi-res pack), but of course like in that game when you look too high in the sky, the buildings look distorted.



 Also moving the camera height up and down would be the problem.