A freeplay-sandbox map pack with 32 maps from all three S.T.A.L.K.E.R. games (and one map made from scratch) with a-life on over 400 smart terrains. There is no story but there are about a dozen repeatable tasks available throughout the Zone. The mod is featured as a modding resource but can still be played on it's own.
Old picture, and this NPC mesh is not in the mod anymore, but he looks creepy. :D