I just recently completed the game on the PC platform. I picket the path that ended with a nuclear explosion, but when the credits played and finished, I attempted to continue my game, but instead, the credits kept re-rolling again and again. Ubisoft, please fix this problem as quick as possible so that we all can keep playing your game.
so i just finished the story line on PC and man was that crazy. but regardless i had this same issue of not being able to play the game after it was beated. originally after the credits it took me back to the main menu and then i selected continue to keep playing (despite the nukes and all) but when i would spawn i would have about one second of play time before it would roll the credits again. so with some tinkering i figured out how to fix the credits.
when you first spawn in, take that split second to open up your world map, the credits shouldn't roll here, then fast travel somewhere, i dont think it matters where. but i did this a few times and on the second attempt it worked , i was able to play the game normally and it didn't roll the credits.
hope this helps everyone wanting to keep playing this amazing game!