Hollow Knight, a cutesy, insect-y metroidvania released in February of this year, is getting its second free content pack in late October. The Grimm Troupe is a loosely Halloween-themed expansion so the release date is certainly thematic.
Gif from Hollow Knight Press Kit
Team Cherry, the studio behind Hollow Knight announced the release date on their blog earlier today. As the game has been distributed through Steam, GoG and Humble Bundle there are several ways to get the update. Steam and GoG versions will be given a free update, while Humble Bundle players will have to download a new version with the content.
The Grimm Troupe will expand the game with a new major quest-line, several boss fights, new player abilities, new enemies, new friends and music. Additionally it adds the ability to create custom map markers to make exploration easier as well as localization for Russian, Brazilian Portuguese and Japanese.