Overall Heroes Harem Guild is a grind game like all games, not a VN or KN. What I found different about HHG is that it has interesting writing and the interactions are not filled with empty options. When looking at game play, the entirety of my hours spent were not considered wasted, and the thrown in humor kept me wanting to read the text a lot more than most of the VNs I play.
Sandbox is not something I enjoy, but there are a few games that make sandboxing an element that works. Games like The Raven and My Early Life are grind games that I want to like, but can't get into because I really don't want to spend the time in a boring grind with no direction of what leads to the next event. HHG lays out hints and directions in good enough detail to keep the game flowing to not frustrate the user. Desert Stalker also does this well enough to keep me watching for new releases.