Niflheim is known as "The Realm of Fog", originally being a realm of endless snow, wind, ice and mist. However, an ambitious Dwarf alchemist named Ivaldi decided to settle a workshop in the land of mist and found a way to harness all the frosty power of Niflheim, creating works of marvel that shocked the realms of both men and Gods.
Unfortunately, the leader of the Aesir, Odin, didn't like the idea of Dwarves creating contraptions that challenged his power, so he intervened with Ivaldi's creations, to which the Dwarf furiously retaliated. As the situation escalated, Ivaldi began to meddle with forces he shouldn't have and ended up cursing the entire fog realm, altering its mist to poison anyone who breathed it, a curse to which Ivaldi was the first victim of. Horrified at what Ivaldi had done to the former ice realm, his son Mótsognir would leave behind a message outside his father’s workshop renouncing his own kind and warning anyone who traveled to Niflheim to turn back.
The snow and ice are nowhere to be seen, the wind doesn't blow anymore and the now fatal mist releases a foul smell. Kratos and Atreus can collect all the Niflheim Ciphers in Midgard in order to access the mist world and traverse the now abandoned workshop to retrieve the realm's exclusive materials like Mist Echoes and Niflheim Alloy.
Ivaldi's Workshop: The only explorable location to date, the workshop is a labyrinth filled with chests containing the rare materials and still active lethal traps left behind, alongside undead beings, Seiðr creatures, Hel-Walkers and rabid beasts.
The poisonous mist makes travel in the workshop limited, depleting Kratos's health after a set period of time, time that can be partially replenished by opening up chests. The Dwarf Sindri that can be found near the entrance of the workshop can also craft equipment that lessens the mist's effects.
Further into the center of the labyrinth are locked chests that can only be opened by exchanging previously collected Mist Echoes. This is also where three Realm Tears also left behind by Ivaldi are located, which like the chests can only be opened by exchanging Mist Echoes.
- Niflheim is one of the two primordial realms in ancient Norse cosmology, said to be the place where Ymir took form. The other primordial realm is Muspelheim.
- If you find a Nornir chest in the first room you enter, where the runes are scattered over the other chambers, don't back out to Sindri when you are through with the workshop, or it will disappear upon re-entry. Instead head up into the central chamber, the workshop enemies and chests will have a full reset but in this case, the Nornir chest stays. That means you have 2 Nornir chests to open every time you make another round through the workshop.
- The rune of Niflhiem is "naudiz" (ᚾ) in the Elder Futhark, which represents the letter "N" and the concept of "hardship."
- The earliest point that Niflheim can be accessed is after Kratos and Atreus escape from Helheim. This applies even in New Game+, where the chest in the peak that normally has the cipher code for the realm will be turned into a useless enhancement to ensure that players won't unlock the realm too early.
- The Realm travel door to Niflheim depicts an abandoned city or workshop, the wind blowing through the empty place and old vines growing through the rubble. On both sides of the mural are Dwarves however these may either be two different statues which have decayed over time or perhaps a before and after depiction of the head Dwarf Ivaldi as he was the first to die from the poisonous mists he released.