Mortal Shell 2 will forgo traditional difficulty modes in favor of a system where players can adjust the challenge by acquiring and equipping special items. Developed by Cold Symmetry, this approach allows for a personalized gameplay experience, letting players either ease their journey or significantly increase its difficulty.

One such item is the Slayer Seal, which enables players to regain health and resolve by successfully executing enemies with powerful riposte attacks. This mechanic incentivizes aggressive play, drawing parallels to the health regeneration through melee executions found in games like Doom (2016). However, using the Slayer Seal comes with a trade-off: it prevents players from earning achievements.

For those seeking a greater challenge, the Gloombound Flame offers a more demanding experience. When brought to Marrow Keep, this item can relight a brazier to summon an NPC named Thestus. Interacting with Thestus allows players to activate "Night Mode," which plunges the game's world into darkness by turning off the sun. This mode introduces a host of new challenges, including altered events, new non-player characters, and additional dungeons, alongside other rewards.

Beyond these prominent examples, Mortal Shell 2 features other items that modify core gameplay mechanics. The Untarnished Seal provides a traditional parry option for melee combat. Alternatively, Vatra's Seal offers a temporary hardening ability, acting as an all-over body shield that protects the player. This hardening effect is governed by a meter that can deplete, leaving the player vulnerable if not managed carefully.

This system of adjustable difficulty through equippable items represents a flexible approach to player-defined challenges, allowing individuals to fine-tune their experience without fundamentally altering enemy capabilities. The game casts players as The Harbinger, tasked with recovering a stolen sacred egg from the Undermether, exploring the world and inhabiting the "shells" of fallen warriors to unlock new playstyles and abilities.