The player controls the Knight, an insectoid warrior exploring Hallownest, a fallen kingdom plagued by a supernatural disease.

The game is set in diverse subterranean locations, featuring friendly and hostile insectoid characters and numerous bosses.

Adelaide-based Team Cherry wanted to create a game inspired by older platformers that replicated the explorational aspects of its influences.

Hollow Knight was well received by critics, with particular praise for its music, art style, worldbuilding, atmosphere, combat and level of difficulty.

The Knight can strike enemies with a sword-like weapon called a Nail and can learn spells that allow for long-range attacks.

The Knight's mission is to find and kill three bugs called the Dreamers, who act as the living seals on the temple door.

Through dialogue with non-player characters, environmental imagery, and writings scattered throughout Hallownest, the Knight learns the origins of the Infection.

Beneath the notice of the Pale King, some worship of the Radiance continued, allowing her to remain alive inside the Dream Realm.

In an attempt to contain the menace, the Pale King used an ancient power called Void to create the Vessels – creatures that could trap the Infection within their own bodies.

The Pale King chose a Vessel known as the Hollow Knight to trap the Radiance, leaving the rest locked in a pit called the Abyss.

After striking a masked bug with the Dream Nail, the lantern summons a mysterious group of circus performers to Dirtmouth, who identify themselves as the Grimm Troupe.

Their leader, Troupe Master Grimm, gives the Knight a quest to collect magic flames throughout Hallownest in order to take part in a "twisted ritual".

"[13][14] Believing that control of the character was most important for the player's enjoyment of the game, the developers based the Knight's movement on Mega Man X.

They gave the character no acceleration when moving horizontally, as well as a large amount of aerial control and the ability to interrupt one's jump with a dash.

The game passed this goal, raising more than A$57,000 from 2,158 backers, allowing its scope to be expanded and another developer to be hired—technical director David Kazi—as well as composer Christopher Larkin.

[10] The game reached a beta state in September 2015 and continued to achieve numerous stretch goals to add in more content after an engine switch from Stencyl to Unity.

[17] The creators of Hollow Knight worked with another Australian developer, Shark Jump Studios, to speed up the porting process.

[18] Initially, Team Cherry planned the Switch version to arrive "not too long after the platform's launch"; subsequently they delayed it to early 2018.

[22] On 3 August 2017, the Hidden Dreams downloadable content (DLC) was released, featuring two optional boss encounters, two songs in the soundtrack, a fast travel system, and a Stag Station to discover.

[23] On 26 October 2017, the second DLC The Grimm Troupe was released, adding major quests, boss fights, charms, enemies, and other content.

[24] On 20 April 2018, the "Lifeblood" update was released, bringing various optimisations, changes to the colour palette, bug fixes, minor additions as well as a boss fight.

[25] On 23 August 2018, the final DLC, Godmaster was released, containing characters, boss fights, music, a game mode called Godseeker as well as two endings.

[28][29][31] Jed Whitaker of Destructoid praised it as a "masterpiece of gaming"[3] and, on PC Gamer, Tom Marks called it a "new classic".

"[2] Adam Abou-Nasr from NintendoWorldReport stated: "Charms offer a huge variety of upgrades ... removing them felt like trading a part of myself for a better chance at an upcoming battle.

"[35] The difficulty of Hollow Knight received attention from reviewers and was described as challenging;[33][34][36] Vikki Blake of Eurogamer called the game "ruthlessly tough, even occasionally unfair".

[32] For Nintendo World Report's Adam Abou-Nasr it also seemed unfair—he had "'so frustratingly hard that I cannot recommend this game' angrily scrawled in [his] notes"—but "it eventually clicked".

[3][35] Critics also made comparisons to the Dark Souls series, noting the mechanic of losing currency on death and having to defeat a Shade to regain it.

[3][34][36] Destructoid praised this feature, as well as the holding down of a button to heal, because "[t]hey circumvent a couple of issues games have always had, namely appropriate punishment for failing, and a risk-reward system".

Team Cherry had previously planned this game as a DLC for its predecessor, but decided to market it an individual title as its content grew too large.