Priboi Story mod for STALKER : Shadow of Chernobyl
Pretty cool Half-Life-esque adventure mod. The base character' sprint was reduced to an horrendous speed, but at the same time the jumping height was increased. This makes it somewhat harder to run from mutants but it also makes walking over long distances pretty boring. The creator also added several new weapons which are great but not distributed properly through maps and harder to spot anomalies.
EDIT: Important characters in the vanilla game suffered a name change. Why on Earth is the Barkeep called "Reba Kapat"?
Anyways, it plays and feels like a 4th STALKER game. Currently stranded on some roofs by the mercenaries at Agropom. Pfft, casuals.