Hollow Knight is as long as it needs to be, and the astonishment of bumbling into a whole new zone dozens of hours in, saying, "How did I miss all that?" is one of its central pleasures.
It's such a breath of fresh air when the so-called Metroidvania has become excessively conventionalized. You play a game like Guacamelee! or Ori and the Blind Forest (which are both very good at what they do), or even go back to an older but slightly unorthodox one like Metroid Fusion, and for all their virtues and stabs at originality, there is just something extremely predictable to the density of the locks and keys and the scope of movement options you can expect. SteamWorld Dig 2 dodges this slightly with the internal contiguity of its zones, since the corridors don't come off as corridors, but even it feels abruptly cut short in some places as a regression to a 10-to-15-hour norm. The particulars shift from game to game, but once you've played enough of these, the overall rhythm of uncovering a map and hitting its major act breaks or embedded dungeons starts to come off as something the developers take for granted. It doesn't help that the term "Metroidvania" (which was always better aimed at the Castlevania side of the family than at Metroid and its direct descendants) has become diluted to the point of being applied to short and barely exploratory games like Shantae and the Pirate's Curse, which is competent enough, but so by-the-book (and easily swept in well under 10 hours) that for me the experience hardly registered.
You know Hollow Knight hit its target well when pretty much every complaint I've ever heard about it—the map system, the deliberate lack of signposting to distinguish a "critical path" from its side branches, the overall scope and length—just serves to reiterate why the game resonates so strongly with players like myself, for whom the experience was rapturous.
Like BotW—or for that matter, Zero Mission (by design) and Super Metroid (perhaps not entirely by design)—Hollow Knight is also incredibly flexible because of its openness to route discovery and sequence breaking. This means it permits a huge spread of clear times from frantic world records to patient completionism. It's extremely roomy in permitting a wide range of highly individuated pathways and personal experiences, in a way that is practically unprecedented in this genre, and it wouldn't have done this so successfully if the sheer quantity of play-space wasn't there to support it. You can't compare this versatility at all to AAA open-world bloat that is nevertheless locked down and compartmentalized into waypoints, mission structures, and story-based gating.
