This isn't a adaptation, they announced it will be different from the game. Being a big fan of the yakuza series, this "alternate universe" reimagining is a amazing story. Keeping key points from the game yet creating a new story.
From what I see in the reviews, people dislike it because its not like the games. That wasn't their point.
Would it have been better as the game? Most definitely, but this reimagination is worth watching too.