Where there is light, there is also shadow. To make objects in a lit environment look more realistic, shadows are required, and they must move along with the light source. The activation of shadows almost always costs valuable 3D speed, so the faster the graphics card, the more intricate the effects can be without hammering performance. In Oblivion, it was possible to invest up to 30% of the graphics power on just facial, leaf and grass shadows.
Older games with standard shadows suggest this effect with a grey circle; the figure always stands on a dark spot regardless of the lighting. The following generation of games mapped the character on the floor like a template, often using a simplified model of the figure itself. This can clearly be seen in Morrowind, as clothing is simply ignored and the naked body structure is mapped on the floor.
Doom 3 represented a minor revolution. Suddenly there were numerous light sources, such as ceiling lamps or spotlights that simultaneously cast dark figures on walls, floors and ceilings. As the player and the monsters moved, the shadows wandered past the fixed positions of the light sources, and became shorter or longer. In order to get on your nerves even more, there were also hanging, flashing and swinging lamps to cast twitching and dancing patterns on the wall.
Current games have a soft shadow that fully maps the figure in considerable detail. Depending on the position of the sun, the mapping of the character and environment is sometimes longer and sometimes shorter. In Stalker or Crysis it is even possible to see the shadowy images of individual twigs or leaves on the floor. Even if this sounds like a gimmick, it is extremely important for perception in real-time games, as it enables movements to be recognized more quickly.