Why would the music and style be treated as more special than the concept of the game ?
Also depends on how 'concept' is defined. Two games where you "unpack things" can be vastly different, but two games where "you unpack things from a packing box and place them on small diorama-like rooms without any objective" is hard to differentiate.
All assets have degrees of genres (platform/shooter/..., rap/classic/..., pixelart/medieval/...). But the amount of things you need to change in order to create an "original work" is not the same for all of them.
Ehm, I don't know whether this supports or hurts your argument, but Crash Bandicoot is 3d (or at least 2.5d) and has an entirely different type of gameplay than either the 2d or the 3d Mario games.
Maybe Megaman is a better example?