A Doom engine in about 2000 lines of C

Ha! really cool! just glimpsing through the code I see lots of multiplications, divisions, and other floating point code. So, for whoever attempts this, I guess the first step would be to turn all the code into fixed point arithmetic

http://msx.gnu-linux.net/doomlike/doomlike.html

Nice related article by David Heremans.

They are different approaches, mine is equivalent to wolfenstain 3d, this other to duke nuken 3d

I feel the best MSX 3D game would be with single color polygons
LMMV on 9990 is a magnitude faster than anything else
the lighting can be better than 486 texture game

things like this


or hard drivin

If you do not want textures, bisqwit's code allows you to compute directly vertexes and draw polygons. The raycasting technique (the one in wolfenstain 3d) would be more clumsy in this regard, as it scans all the view directions in any case, so plotting the screen column by column is more natural.
Naturally the rendering speed depends on how long you need to plot a generic polygon (usually a trapezoid) with respect to a set of single color columns (which in turn are vertical lines or boxes according to the angular resolution).
About the underlying math, it is hard to say, as bisqwit's code does less operations (dealing with the list of vertexes of the convex hull to be represented), but involving more math per vertex.
Raycasting instead, basically casts a ray per view direction, so it does simpler operations (using mainly integers) but repeated for each column.