..\Ubisoft\Crytek\Far Cry\Levels\[mod folder name]

"..\Ubisoft\Crytek\Far Cry\Bin32\FarCry.exe" -map "map [map name]" -game_DifficultyLevel "game_DifficultyLevel 4" -Devmode

Skill: game_DifficultyLevel can be 4 (Realistic), 3, 2, 1, 0 (Easy).

"C:\Program Files\Ubisoft\Crytek\Far Cry\Bin32\FarCry.exe" -map "map aecanyon" -game_DifficultyLevel "game_DifficultyLevel 4" -Devmode

OR installation for mods (indicated by below):

..\Ubisoft\Crytek\Far Cry\Mods\[mod folder name]

Command Line:

"..\Ubisoft\Crytek\Far Cry\Bin32\FarCry.exe" -Mod:[mod folder name] -devmode

Note that the -Devmode parameter is added to enable game access to the devmode.lua file located in the main game directory. This can be enabled in order to use cheats in the game, including saving and loading outside of the pre-programmed checkpoints (which are missing or too far apart in many custom maps). See this page for full information. The basic save and load script to add to the end of the devmode.lua is as follows:

Input:BindCommandToKey("#Game:Save('Quicksave')","f9",1);
Input:BindCommandToKey("#Game:Load('Quicksave')","f10",1);

This binds f9 to quick save and f10 to quick load. See the tweakguide for more information. Note that devmode is not recommended for some mods as it can break scripted events. Check the readme in each mod for warnings.