The new Deus Ex games have good standalone DLC.
I didn't like how Human Revolution shoehorned The Missing Link into the middle of the story, but gameplay-wise it was a lot of fun. System Rift, for Mankind Divided, was also great fun and, with a small new neighborhood to explore, had a good balance of exploration and combat. Haven't played A Criminal Past yet but the desert prison environment is refreshingly new and it's supposed to be very good.
I didn't like how Human Revolution shoehorned The Missing Link into the middle of the story, but gameplay-wise it was a lot of fun. System Rift, for Mankind Divided, was also great fun and, with a small new neighborhood to explore, had a good balance of exploration and combat. Haven't played A Criminal Past yet but the desert prison environment is refreshingly new and it's supposed to be very good.