Coastline to Atmosphere is a big Single Player Modification for Half-Life 2. It's actually 15 Single Player maps with a story that links them together. Leon Stephan Brinkmann took about 1 year to create this. He's done an excelent job to create this. With new models, such as a Keycard model, Tree models, a new shiny metal texture. And new sounds from the games Medal of Honor, Call of Duty, Soldier of Fortune 2, Max Payne 2, Cold Winter and a whole lot of ambient sounds.