Older version saved games.
 

OK, I can't say this will work all the time, in fact I remember trying this once before with little success. I have MoW Steam version 1.17.5 and a retail version 1.02. When my Steam version auto-updated I could no longer play my 1.11.3. saved games which kind of bugged me. Like I stated earlier I can't say this will work all the time but I went into a 1.02v. saved game folder and opened the "status" file and simply changed the {game_version "1.02.0"} into {game_version "1.17.5"} and it worked. I did this with two different 1.02v. saved games and one 1.11.3v. If anybody decides to try this make sure to backup your file.