Originally Posted by Edge
Doom 3's models are between 2,000 and 4,000 polygons each. Backgrounds vary, but I'd guess they peak at around about 20,000 (probably substantially less most of the time). So at most, maybe 30,000 polygons on screen at once in Doom 3. Half-life 2 a bit more, but still not by a huge amount. By comparision, Half-life 1 and Quake 3 used had around 3,000 polygons in a single scene.
Actually, it seems higher polygon counts are more prevalent in console games than PC games, partially due to less effects being used on them. For example, Ferrari F355 Challenge on the Dreamcast (a console using 5-year-old technology) had areas with over 50,000 polygons on the screen, and it ran at 60FPS. Of course, it only used basic textures and specularity maps for almost all of them, no fancy bump mapping, normal mapping, or advanced lighting effects, but it still looked pretty decent. At this point, more polygons aren't really a big deal since the camera is almost always far enough away from the characters and geometry that the extra smoothness isn't very noticable. Also with displacement mapping and offset mapping, you can simulate the effects of millions of polygons in a single surface. Just take a look at Humus's offset mapping demo: had the floor and walls been built strictly from polygons without using any mapping, it would've probably used well over a million polygons in the scene. But, thanks to the surfacing effects, it looked almost exactly the same except it only drew about 10 polygons.
Although there are some rough edges in Doom 3 that could've been smoothed out with more polygons, in-game it looks great but sometimes cutscenes zoom in far enough that you can see a lot of pointy edges on the characters.