YMMV / Mortal Shell

• Goddamned Bats: The wraith enemies that haunt each temple are rather squishy, going down in a few hits. However, they can cast highly damaging AoE attacks with little wind-up, ranging from flames that inflict burn damage on you, to ice spikes that freeze you in place, to obsidian spikes that could potentially knock you off the nearest Bottomless Pits.
• Magnificent Bastard: The Old Prisoner is an ancient and powerful being imprisoned in Fallgrim Tower, until The Foundling frees him. The Old Prisoner would then task The Foundling to retrieve three Glands where he plans to use them to ascend from Fallgrim. Upon learning that The Foundling, not him, is meant to ascend, The Old Prisoner battles them declaring if he's not able to ascend than no one can.
• Minimalist Run: On a game that's already Nintendo Hard as it is, it's quite possible to finish the game without ever possessing any of the Shells or you can give up all your Shells, upgrades and Glimpses, trading away the Foundling's humanity. It compensates by having high stamina. There is even an achievement for beating the game without ever possessing a Shell.
• That One Achievement: Speaking of which, the achievement in question, "Forever Alone" (and the related achievement "Life Is Suffering", for beating the game with the Dark Obsidian Foundling skin, which you get by visiting the altar that permanently removes all shells from the game). Fighting in your Foundling form doesn't only mean you become a One-Hit-Point Wonder, it also completely deprives you of the various passive upgrades which give each shell the edge in combat, leaving you with the bare minimum capabilities^note although the Dark Obsidian Shell at least gains the ability to harden in mid-air. Aside from high stamina (which isn't even all that impressive as Tiel has similarly high stamina), there is NO advantage to playing as the Foundling, and attempting to beat a game as brutally difficult as Mortal Shell when you're so laughably fragile (especially considering how spaced-out the game's checkpoints are) is a challenge only the truly hardcore should attempt.
• That One Level: Each time you defeat a temple boss and rip out their associated gland, the world goes into the Fog state. Aside from spawning an ever-present fog that limits your visibility, the state also darkens the temples' interiors, alters their layouts in some places and spawn a large number of powerful enemies, which you'll have to go through in order to make it back to the Fallgrim Tower and give the gland to the Old Prisoner, returning the world to its normal state.
  • All this makes each "fog runback" nerve-wracking enough, but special mention goes to the runback through the Eternal Northax, which forces you to traverse a narrow walkway while being shot at by an entire firing squad of enemies with Automatic Crossbows. This segment is particularly brutal if you're playing as Tiel, whose small HP pool often results in him going down in a handful of hits.