Fatal Fury: City of the Wolves continues to deeper its ties with Street Fighter. Last year, two of the DLC characters coming to the game were Chun-Li and Ken, and while the new collab doesn't include new characters, it's a fairly substantial infusion of Street Fighter.
The two major points for people who mostly play versus matches will be two new costumes and a stage. The two costumes are for Rock and Preecha, turning them into Luke and Juri respectively. As for the stage, it seems to be set in Metro City, and represents the bonus parry stage from Street Fighter III: 3rd Strike. If you pay attention to the background, you will also find a lot of references hidden in there.
Surprisingly, this collab will also add some new content to the game's single-player mode. If you play EOST, you will find a new collab story, new skills, and new enemies, like Carlos Miyamoto, the iconic refrigerator enemy from World Tour, and the box wearing gang members. You'll also get a special boss battle against Kage Terry.

