Tristram is a very prominent town in the lore of the Diablo series. The town serves as the main gameplay hub for the player In Diablo 1 as they explore and fight their way through the Labyrinth underneath the city.
The remains of the town are revisited by the player in Diablo 2 and 3.
Lore and Backstory
Several Hundred years before the events of Diablo, a team of the Horadric order led by Deckard Cain's ancestor Jered Cain defeated and imprisoned the last of the Prime Evils, Diablo, in a soulstone. The order entombed Diablo's soulstone deep within the earth in a massive labyrinth in the western kingdom of Khanduras and constructed a Monastery to guard it.
With the Prime Evils, Diablo and his two brothers Mephisto and Baal , being safely sealed into soulstones the world entered a long period of peace. Over time the Horadric order's membership declined to more or less non-existence and the monastery feel deep into disuse and disrepair.
Years later a small town called Tristram was built near the ruins of the old monastery and its' massive labyrinth dungeon, Tristam's new inhabitants being completely unaware of the great evil that lay dormant underneath.
The Darkening of Tristram
A few years before the events of the Diablo Series an Eastern King from Kehjistan named Leoric came to Khanduras on behalf of the Zakarum faith and established a religious kingdom with himself as the ruler. He appropriated the abandoned Horadric Monastery on the outskirts of Tristram to serve as his base of operations, turning into the Tristram Cathedral and proclaimed Tristram to be the capital of his Khanduras Kingdom. The locals mistrusted this sudden unasked for ruler, but over a short time warmed to his kind and virtuous guiding hand.
Unbeknownst to Leoric his trusted advisor Lazarus was a servant of Mephisto, and it was his advice to select Tristram and the Monastery as their base. Leoric unwittingly had set into motion events that would lead to the Three Prime Evils walking free in the world of Sanctuary once more. Shortly after arriving in Tristram Lazarus would locate Diablo's soulstone and shatter it, allowing the Lord of Terror's essence to search for a host body. Diablo would attempt to possess Leoric but was unsuccessful due to the King's strong will, instead he possessed Leoric's young son Albrecht. Leoric however was deeply affected by the failed attempt. Paranoidly delusional from Diablo's corruptive influence as well as the the loss of his son, Leoric would begin systematic executions of his subjects, including his own wife, and started a war with their former ally the Kingdom of Westmarch.
One of Leoric's knights, Lachdanan, would return from the disastrous Westmarch campaign and determine the King to be a hopelessly lost cause. He would slay the mad King, but not before he and his men were cursed into eternal servitude to the now undead mad monarch and a horde of demons set loose upon the citizenry of Tristram. The mad King would arise as massive a Skeleton King. Along with a monstrous Butcher and Diablo, Leoric and his former Advisor Lazarus would terrorize the remaining citizenry.
It is in the midst of this chaos that the Three heroes, Moreina the rogue, Jazreth the sorcerer and Prince Aidan the warrior (Leoric's Eldest son) would arrive in Tristram.
Appearances in the Diablo Series
Tristram has appeared in every Diablo game to date and is one of the most prominent locations in Sanctuary.
Notable residents : King Leoric, Queen Asylla, Prince Albrecht, Prince Aidan, Deckard Cain, Leah (New Tristram), Adria the witch, Gillian, Wirt the Peg-Legged Boy, Ogden, Griswold the Blacksmith, Pepin, Farnham the drunk, Bron the Barkeep (NT), Mayor Holus (NT), Captain Rumford (NT), Brother Malachi the Healer (NT), Radek the Fence (NT) and the Stranger/Archangel Tyrael (NT).
All the events of Diablo take place in the Tristram vicinity. The town serves as hub for the player where he or she can buy items, weapons and armor and converse with NPCs. The Cathedral and its' catacombs comprise the levels of the game.
The three Heroes would prove victorious in vanquishing Diablo by slaying his host Albrecht and embedding Diablo's soulstone's shard into Aidan in an attempt to contain his evil once more, but the victory was a Pyrrhic one as Diablo began corrupting Aidan.
Hellfire is an expansion to Diablo released and developed by Sierra Entertainment. It's canoncity is doubtful as the events within it have never been referenced again in the Diablo series, but it entirely takes place in Tristram as well. Hellfire adds a few playable areas and classes but more or less is a completely optional addition to the base game.
Notable residents only in Hellfire:
Celia, Lester/Complete Nut
Shortly after the end of Diablo 1 Aidan, now known as the Dark Wanderer, would leave Tristram on a macabre quest to the East to free the other two Prime Evils. Within a short time after his departure, a new horde of demons would arise from the Tristram Cathedral and slaughter nearly every remaining resident of Tristram save for Deckard Cain who they imprisoned in a massive cage. His former companions would prey to Diablo's corruption as well. Moreina became the Blood Raven and Jazreth became the Summoner. Both would be minibossess the new heroes would have to defeat In Diablo 2
Tristram is only shown briefly in Diablo 2 and is playable on the mission to rescue Deckard Cain. The town is one of the few non-randomly generated maps in the game and retains a virtually identical layout from the original game. The town is depicted as being in ruins with most of the NPCs and NPC vendors from the first game being heavily implied to having been slaughtered right where they once stood. Notable exception includes The town's blacksmith Griswold was turned into an undead miniboss encounter and Adria and Gillian both who managed to flee in time. The Cathedral and catacombs are not viewable or playable.
The Tristram area also is the location of the infamous Easter Egg in-joke "secret cow level".
Diablo II: Lord of Destruction
Tristram does not appear in Lord of Destruction beyond what was already in the base game
Nearly Two decades later an attempt to revive Tristram has already floundered as "New Tristram" is a shabby run-down town of shacks. New Tristram arose as a boom town as enterprising merchants set up permanent installations to profit off the adventurers who would try their luck in the catacombs beneath the Cathedral in hopes of finding glory or ancient treasure. Over time the adventurers stopped coming though as word spread of the grisly fates of those who foolishly braved the catacombs.
New Tristram serves as the opening area of the game in Act 1 as the Nephalem (player character[s]) would help Deckard Cain and his ward Leah combat a newly re-arisen King Leoric and the witch Maghda's coven. The player revisits Old Tristram called "The Old Ruins" in game during the quest to kill the Skeleton King Leoric once and for all.
Tristram does not appear in Reaper of Souls beyond what was already in the base game.