Game 2 Editor
Game 2 Editor is a prototype 3D editor originally planned for unreleased sequel to Operation Flashpoint, which eventually became Arma 2.
The editor is present in the game data, but is hidden and cannot be accessed by any button. To open it, press Ctrl + E in the main menu. This method is no longer available in Arma 3. However, Eden Editor renders the editor obsolete anyway.