"As part of the rules for the competition level designers were only allowed to use assets that shipped with the game; trying to come up with ideas was initially quite tricky because of being so used to making just about everything for previous Quake 4 levels.
I had been toying with an idea of doing something with pillars for a previous level and thought this competition might be a good opportunity to explore that. So the level started out as a pair of carefully shaped and textured pillars - different ideas were tried, despite their apparent simplicity. Once they had been sorted out from the point of view of size and scale, all the components were collected together and 'converted' into a func_static (a brush based 'model'); this initial prefab set the style, tone and relative size of everything else in the map.
The column prefab was duplicated and placed, semi strategically, in Radiant just to get some idea of the size, shape and form of potential level layouts. Using this temporary placement as a starting point, a couple of areas we're then padded out by adding 'structure' (walls, floors, ceilings) and as the rest of the layout progressed areas were incrementally built up - better textures and lighting, more detailing and so on; in the absence of copious amounts of concept sketches and given the short time period associated with the competition, it was thought prudent to have built up in this way so as to establish a 'look' early in the process - normally you'd want to block out a level and its layout in rough, making a number of 'detail passes' to increase texture and architectural detailing as the project progresses.
Although the use of custom models wasn't permitted and level was 'tech' in nature I did want to find a way to incorporate some 'organic' content somehow so, I fell back on an old brushmonkey skill, 3 point clipping, to shape some 'raw' brush blocks into rocks, which provided a nice contrast to the manmade tech content.
Whilst all this building is going on, lighting is being worked on at the same time. Because of the way lights work in the Quake 4 engine (idetech 4) it gets 'expensive' to have too many in place; all minor lights have shadows turned off as well as having a light detail level set. Instead it's better to approximating the look you're after; lights are placed to illuminate 'areas' (the 'sum' of a lot of smaller lights) rather than as a lot of separate individual light objects (lights placed directly in front of light sources).
Allied to the lighting is the addition of a thin fog which is useful as it tends to soften the general appearance of everything and take the sometimes harsh contrast out of the dynamic lighting. The colour used depends on what you want to do but I used a greenish-grey colour so as to contrast a little against the orangy-browns of the textures (the fog doesn't always need to be the chromatic opposite colour to the lighting/colour theme - orange them/lights -> blue fog), the overall effect lends a lot of atmosphere to the level as well as giving the appearance of 'soft' lighting and shadows."