[Hellfighter]

i know some game the singleplayer maps you could make new singleplayer maps, but you would have to name them the same name already made and replace the stander maps

one make a new sp-map and replace the older sp-maps, by using the same name sp-map this don't always work all the time, but there is an small chance it could work

i know in FarCry 1st some made mods (MOTTO-4) with total new sp-mission for the game