Harp Solitaire is best described as Klondike with two decks plus one particularly annoying rule.
Cards can only be dragged in groups (of alternate colours) when the group starts with a King.
These groups can then only be dropped on an empty space.
This makes the game too fiddly for my liking:(
Fun rating: not particularly high!
I much prefer Endless Harp.
These games are related to Harp Solitaire, some more so than others.