Notice this Steam page is "
Silent Hunter: Wolves of the Pacific"
https://store.steampowered.com/app/1...f_the_Pacific/
That would be version 1.3, while this Steam page is "
Silent Hunter: Wolves of the Pacific U-Boat Missions"
https://store.steampowered.com/app/1...Boat_Missions/
and that would be version 1.5, as an "upgrade" for the v1.3 package. Note that under the title, the Steam page says "
This is an expansion for Silent Hunter: Wolves of the Pacific and requires the Steam version of the original game to play." So you do need both versions from Steam.
When put altogether in a single package though, as in this Ubisoft store page
https://store.ubisoft.com/us/game/?l...&source=detail
While it says "Gold Edition", it is version 1.5 also.
Why Steam does theirs that way is beyond my comprehension... If their v1.3 could be updated to the Ubisoft v1.4 download, then maybe it would be useful, but it cannot. The only way to update the Steam v1.3 is to use the Steam v1.5 U-Boat Missions purchase...
