An ASSETS file is a game resource archive used by Unity, a program used to develop 3D games. It contains game resource files such as meshes or textures for 3D models. ASSETS files may also store game databases.

ASSETS files are typically seen when building a Unity development project into an executable game deliverable or when modding a game. If you are looking to alter gameplay of a game, such as how characters or the environment appear, you can edit ASSETS files and place them back in their directory. ASSETS files are commonly stored in the "Assets" folder in the Unity game directory. NOTE: You can use the Unity Assets Bundle Extractor to edit, export, and import ASSETS files.