Core Keeper's free Riders of the Underground update launches on 21 September with rideable cattle mounts, a hookshot, a new Moss sub-biome, a trio of hydras, plus new pets, weapons and armour.
Core Keeper's underground has a new way to travel. The free Riders of the Underground update is available today on PC, Nintendo Switch 2, Nintendo Switch, PlayStation 4, PlayStation 5, Xbox Series X|S and Xbox One. It adds rideable cattle, a hookshot and a new Moss sub-biome. Coverage from IGN and PC Gamer places the launch on 21 September 2026 across all seven listed platforms.
Mounts change travel
The update's biggest addition is the ability to ride friendly cattle. Players can name their animals and set how they behave. An animal can stay in place, roam freely or follow the player as a companion. Denfaminicogamer's coverage points to those settings, which give the mounts a practical use beyond decorating a settlement.
Cattle now have a job beyond the base. A named animal can carry the player around, or stay nearby as a familiar presence, depending on how it is managed. The announcement does not give movement speeds or combat benefits. The confirmed gain is easier exploration, not a wider change to player progression.
Hookshot reaches gaps
The new Hookshot deals with one of the underground's clearest travel problems: open pits and chasms. It lets adventurers grapple across them instead of building paths or bridges. That should make expeditions less dependent on carried construction materials. The GamesPress event roundup describes the tool as a way to cross chasms without building bridges.
The Hookshot changes how players use spaces that already exist. It does not add a separate traversal map. Its confirmed purpose is simple. Pugstorm and Fireshine Games have not shared details about its range, cooldowns or restrictions, so its wider effect on route planning is still unknown.
Moss enters the ruins
A new Moss sub-biome has appeared inside the Forgotten Ruins. Lush greenery now fills parts of the stone ruins, adding a different look to one of Core Keeper's established underground areas. IGN and PC Gamer both describe the moss area as an expansion of the Forgotten Ruins, not a separate world.
The update also adds several pets with individual abilities, along with new weapons, accessories and armour pieces. It includes quality-of-life improvements too, but the supplied announcement does not list every change. The main features are clear. The wider item and convenience package is not fully detailed.
New threats underground
Later promotional coverage adds combat to the exploration-focused update. PC Gamer's report on the official trailer highlights a trio of hydras alongside the rideable mounts and new sub-biome. The available material confirms that they appear in the trailer's feature mix. It does not establish their exact abilities, encounter structure or rewards.
Seven platforms on launch day
Riders of the Underground launched on 21 September 2026 on PC, Nintendo Switch 2, Nintendo Switch, PlayStation 4, PlayStation 5, Xbox Series X|S and Xbox One. Fireshine Games has presented it as a free update, not a separately priced expansion. The announcement also includes a trailer. Players can find Core Keeper on Steam at the Steam listing.
The Switch 2 version arrives alongside the existing Nintendo Switch release. The update also reaches both generations of PlayStation and Xbox hardware. That broad release gives the new mount system a useful point of comparison with another Switch 2 launch. The central fact remains the same: Core Keeper's new content is coming to the listed versions rather than being limited to newer hardware.
No independent performance testing or review evidence is attached to the announcement. The available facts point to a substantial exploration update with a new mobility tool, a new sub-biome, more collection options and the hydras shown in later promotional material. They do not establish frame-rate changes, platform-specific differences or the full scope of the quality-of-life work. Based on that evidence, Riders of the Underground looks like a focused expansion of how players move through Core Keeper, not a total redesign.
Mounts and grappling tools solve different movement problems. A mount supports repeated travel across reachable terrain. A hookshot deals with a specific gap in the environment. That makes Riders of the Underground a meaningful free update because its clearest additions change the basic act of exploring instead of only adding inventory items. Players know the update's main purpose today. They still cannot judge the unlisted changes or platform performance beyond the confirmed release across seven platforms.
