Forge's sim mode looks up decks by NAME in its own %APPDATA%/Forge/decks/commander/ directory. Passing a full path like D:\...\precon-decks\Counterpunch.dck causes 'Could not load deck'. Now strips the path and .dck extension so Forge sees just the bare name (e.g. 'Counterpunch') and finds it in its deck folder. Precon .dck files must be copied to %APPDATA%/Forge/decks/commander/ for Forge to find them.