I just recently finished playing the fourth Shovel Knight campaign, "King of Cards," where you play as King Knight. It seems to be the most unique of the later campaigns, with much shorter levels that are entirely new aside from some of their art assets. Plus there's this whole game within a game with the Joustus cards.
The moveset is a little awkward to get used to, but once I did I had loads of fun with it. The story also has some genuine pathos to it. King Knight is a character who could have had a lot of love in his life, but was too narrow minded in his ambition, and too selfish to accept the love he had around him. There's a scene near the end which intentionally mirrors one in the main Shovel Knight campaign, and it legitimately brought a tear to my eye.
Enjoyed the hecc outta this, would be curious to know if any others have played.