I am not opposed to the same plot concept being used and reused. I admit I don't have much tolerance for endless vampire stories. But even there, I think there are exceptions, tales that are unique.
By "unique," I don't mean avant-garde or "rule-breaking."
I want story, not some stream-of-consciousness experiment.
"Unique," for me, refers to a story that is memorable and engaging. It is different for HOW it handles material, not for trying (impossibly) to invent new material.
What makes On or Off unique is not only that the characters have an actual task/account/app to complete (getting that work completed underpins the volumes so far)--the characters also retain core characterizations.
As I mention in the post on Semantic Error, a good romance keeps the characters' individual oddities even as they fall in love. The characters don't abruptly turn either coy or flawlessly understanding and affectionate. They continue to be idiosyncratic. 
In On or Off, Kang keeps his poignant awareness that romance requires negotiation. He misreads Ahn more than once; unusually for an alpha character, he not only takes responsibility for his miscalculations, he studies his lover, whom he finds endlessly surprising. His older age (by about 15 years) aligns with his ability to assess how he and Ahn are able to become significant others.
Meanwhile, dedicated, hardworking, charismatic yet guileless Ahn goes at everything in his impulsive yet tactful way (as when he covers for Mina's bluntness). With Kang, he is straightforward yet abashed. Being in love enhances those qualities!
Ahn and Kang don't transform into blokes who react in the "proper" romantic ways. Rather, they react to their relationship as individuals.
