If you want to skip ahead to a specific mission like "Eagle's Nest" or "Nuclear Infiltration" without playing the previous ones, use this shortcut:

At the Main Menu, press Left Ctrl + Left Shift + F9 simultaneously. Advanced Console & Shortcut Commands

: (Replace X with a number 1–14) Starts the game directly at that level.

If you're on Windows 10 or 11, consider using the Neonix Remastered Patch , which stabilizes the game for modern screens and includes built-in debug menus. IGI 1 Cheat Codes and Unlocks Guide | PDF - Scribd

: Displays technical info and coordinates in the top left. Pro File Mod: The "Invisibility" Hack

For players who find the AI too aggressive, you can effectively turn off enemy detection by modifying the game folders.

Many players use third-party IGI 1 Trainers to enable features like "No Reload" or "Super Jump".

Type (case-sensitive on some versions, but usually lowercase nada works).

Since many original codes were designed for the demo or specific patches, they might not work on every digital "Full Version."