Mortal Shell II adds 15 dungeons in the free Rotten Autumn update

Mortal Shell II’s Rotten Autumn update adds 15 dungeons at no extra charge. Team Mortal Shell announces it as available on Steam, PS5 and Xbox in its October 20, 2026 announcement. The free additions also include Photo Mode, new Shell Shades and an alternative soundtrack.

The announcement’s free-content offer applies to the Rotten Autumn additions; it does not establish the price of the game itself. For players considering a return, the update combines additional places to explore with changes to the game’s appearance and music.

New dungeons, Tarstones and a ghost

The 15 new dungeons expand the exploration content, although the announcement does not describe their entry requirements or difficulty. That count establishes the number of additions, rather than how long they will take to complete.

The update also lists 10 new Tarstones and separately mentions a sheep-specific Tarstone. The wording does not establish whether the sheep-related addition belongs to that group, so the mentions should not be combined into a larger confirmed total.

Another addition is the ghost of a lost Shell, which offers cryptic notes. That description introduces a new mystery without establishing a quest structure or promising a particular reward.

Further polish and bug fixes accompany the content. These are described collectively, so players waiting for a particular problem to be resolved cannot treat the announcement as confirmation of that individual fix.

Photo Mode and music from Sakis Tolis

Photo Mode joins the game alongside lighting presets for Nightmode and graphics settings named Overkill. Availability of the individual settings across platforms is not detailed. Overkill is a settings label, rather than a confirmed performance improvement.

The alternative soundtrack comes from Sakis Tolis of Rotting Christ. It is an in-game musical addition; the announcement does not establish a separate commercial soundtrack release. The lute also receives an Impervious appearance accompanied by additional tunes, extending the musical changes beyond the alternative score.

New looks for every Shell

New Shell Shades are announced for every Shell, while the Harbinger Pumpkin helmet adds an autumn-themed option. Their unlock conditions and availability period are unspecified, so the seasonal presentation alone should not be read as a deadline to obtain them.

Rotten Autumn’s clearest draw for exploration is its additional dungeons; Photo Mode, Shell Shades and the musical additions offer other ways to revisit the game. The announcement confirms free additions across the listed platforms, while leaving the finer details of access and settings availability open.

See also our Mortal Shell II game page and our Mortal Shell II article covering details from the October 13 announcement.