A subtle "Special Edition" or "vanilla plus" version that adds bug fixes, replay value, extra functionality, content and atmosphere to the game, all while retaining that overall vanilla feeling, rather than the feeling of a vanilla game with various mini-mods tacked on as an afterthought.
The Options Pack for Call of Pripyat: Special Edition v0.9 includes a proper hand-merged patch for AtmosFear 3 by Cromm Cruac and no longer requires the use of Smart Mod Manager. The order for installation is: Call of Pripyat: Special Edition v0.9 > AtmosFear 3 > AtmosFear 3 Patch > Changes you want to use from the Options Pack.