If you meant a different "FM" (e.g., financial management, frequency modulation hardware), please clarify. This guide assumes the classic sports management simulation game. 1. What is it? An "FM Modifier" (often FMRTE – Football Manager Real Time Editor) for FM 2008 is a third-party tool that allows you to edit your save game data while the game is running . Unlike the pre-game editor, it changes attributes instantly.