Unlocking all missions in Project I.G.I.: I'm Going In typically requires a mix of cheat codes, developer console commands, or save file modifications, as the game does not have a standard "Unlock All" button in the menu. Method 1: Instant Mission Skip (Cheat Code)
For some versions of the game, you must enable "Cheat Mode" first before special commands work: At the Main Menu, type nada.
This is the fastest method to unlock all levels without playing through them. Launch the game to the Main Menu. Press and hold Left Ctrl + Left Shift + F9 simultaneously.
Step 2: Locate your I.G.I. Save Folder Navigate to where your game is installed. The default path usually looks like this: