Guarda, io ho appena risolto (dopo tanti, ma tanti vani tentativi), seguendo questo passaggio di una guida su Steam:
-Go to "C:\Users\Administrador\AppData\Roaming\The Creative Assembly\Rome2"
-Then delete the Rome2 folder.
-Once removed go to "C:\Program Files (x86)\Steam\SteamApps\common\Total War Rome II\redist"
-Then open the files listed below in that order and click on repair for each one, the last one doesn't have a repair window pop up, instead you will see a small loading bar,
1-vcredist_x86-90.exe
2-vcredist_x86-100-sp1.exe
3-vcredist_x86-80-sp1.exe
Then just proceed to load your game and it should then go onto the main menu.
Spero ti sia d'aiuto, good luck!
.
MegaMan-X