Cheat mode:

Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the “defuser.ini” file in the game directory. Set a key binding to the following codes (for example, “F10=fly”. Then, press the corresponding key during game play to activate the corresponding cheat function. Note: Any active codes are disabled when a new area loads or intermission sequence plays.

Effect / Code
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God mode - god
Disable clipping - ghost
Flight mode - fly
Disable fly and ghost codes - walk
Teleport to pointer - teleport