Dwarf Fortress. Install a graphics pack if you're insufficiently autistic, then make a demigod adventurer and kill everyone in your starting village. Thanks to the god-tier combat system, you can:
>grab, lock, and break every individual joint
>grab someone by the head and gouge out their eyes, leaving them to briefly wander aimlessly before standing still, unable to move
>bite/pinch off noses, lips, ears
>at high enough skill levels, you can reliably strike hands, feet, and individual fingers/toes with a weapon
>if a character falls unconscious due to pain (usually from broken bones), a direct hit to the head, or blood/air shortage, you can target any part of their body for a direct hit
>as long as you keep blood loss to a minimum, you can keep people alive as long as you want
>nerve damage and lost limbs are permanent, so you can travel away and come back later and everyone you fucked up will be just as crippled
And if that sick shit ain't enough for you, you can:
>mod a playable race to have fire breath and melt people
>set up a playable race with injectable venom (stinger/fangs) and inject shit into people
>modify the syndromes that said injectable venom causes, which can be anything from paralysis to literally eyes rotting out of heads/blood boiling in veins
Adventure mode not your thing? It's harder to master, but in Fortress mode you can:
>line your fort entrance with dozens of auto-spear floor traps and make goblin kebabs during your first invasion
>embark on a volcano and set up a retractable bridge over the caldera, dunking whoever happens to be passing over it
>lock children in a danger room of spear traps loaded with wooden spears, ensuring that any dwarf that survives the horrific bludgeoning will be a hardened veteran by the time they come out
>chain up citizens in a dungeon, where they will be periodically beaten savagely by your appointed hammerer
Dwarf Fortress: More complexity just means more ways to create suffering(TM)