This simple design is actually what makes these maps so advanced.
Its easy to creaty everything with many blocks and adding
models in every corner.
But these guys make maps for games! and not for showing
how nicely they can make certain deatures of the map.
The performance is an key issue.
Also the maps are made in a clean style. Blocks are snapped to
even coordinates.
Wed ist doing the biggest error, for not snapping the edges of blocks
on even values by default. Thats why all the people here complain about
the long visibility calcualtions. (wich then are switched off as a result)
When I do a map cleanly with the righ alignment of blocks, then the
visibility calculations only need some minutes even for big maps.
Many users dont even know about these technical requirements of BSP.
They put blocks and use the BSP Subtract option so that the result looks nice.
But they overlook the problems with that to the BSP routines. Its simply
not the same as in Modelling programs, where only the polycount is important
and not the position of the polys.
Also everyone talks about pure model maps. But a decent BSP Map done correctly
with good textures and lighning is looking still better than what I see
as "model only" maps. There is still so much potential in BSP,
its just that making these maps need skill, technical knowledge and
a good editor.
This is for example a map from Unreal Tournament 1,
and it runs on rendering technology from 1998/99.
There are no huge textures, shaders etc.

BSP is still very powerfull if the user has the skill in it.
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Recreating .map from compiled bsp levels, unfortunatly works
very poorly. The blocks are messed up then, it more for looking at
the way the leveldesigner handeld certain details.
If I could run precompiled Quake BSP maps from modders on 3dgs, it would be great,
since acknex levels are very much based on the the old quake format.