What is an S3O file? An S3O file is a 3D model used by games with the Spring RTS game engine, such as Evolution RTS, On The Edge, and Zero-K. It contains model information in the Spring 3D Object (S3O) format that dictates the shape of an object, such as a vehicle, item, or character. S3O files are not meant to be opened (the game loads them), but users may open them to modify their appearance with an editor (e.g., Blender with an S3O plugin ).

More Information Only games using the Spring RTS game engine and its forks (e.g., SpringBAR) use the S3O format. Therefore, you will likely only find them in the installation directory of a Spring RTS game. While most gamers will never encounter S3O files, modders may open and edit them and place them back in the original location. Modders may also create S3O files from scratch or other 3D models and export them as S3O files for game use.