https://www.gamespot.com/articles/our-gran-turismo-review-wont-hit-until-november-he/1100-6454198/

I published a short preview a couple of days ago to highlight some of Gran Turismo Sports' unusual touches, but more importantly, to point out that PVP is everything in this game. I can't recommend GT Sport if you're looking for a rich single-player experience as it's incredibly light at launch. The day may come when the campaign consists of more than bite-sized challenges, but for now, those are all you have when playing solo, and they're better viewed as very specific training missions for the big show: online cups and championships.