If the nada method is not working on your specific version of the game, the most reliable "fixed" method is to replace your game’s save data with a 100% completed file. This is often referred to as an . How to Use the Fixed Savegame Method: Download a Project IGI 1 Completed Savegame file.
If your cheats or other methods are failing, the issue is likely related to compatibility or input devices. igi 1 all mission unlock key fixed