Exact il faut extraire les textures correspondantes des fichiers counter strike shared.gfc, source models.gfc et source materials.gfc.
(Short tutorial on how to get cs_assault in L4D:
1) Get the latest NET Framework.
2) Get GFCScape.
3) Extract materials, models and maps from counter strike shared.gfc which is in steam/steamapps to your L4D demo folder in steamapps/common/left 4 dead demo/left4dead.
4) Do the same with source models.gfc and source materials.gfc.
5) Run L4D, Enable Developer Console in Options. Type changelevel cs_assault in console after you have started a new singleplayer game.
6)Enjoy playing on Cs_Assault!)