It’s time to again experience the hell that launched a video game genre.

Diablo III’s Patch 2.4.3 is now live, and it brings a host of changes and content that celebrate the hack-‘n’-slash role-playing game franchise’s 20th anniversary. The most noteworthy addition is The Darkening of Tristram, which brings the dungeon from the 1996 classic to Diablo 3.

““The dungeon is the Diablo 1 experience reimagined in Diablo 3,” a Blizzard representative said in an email. “Players will venture through a reimagined version of the original cathedral and keep an eye out for some familiar items, including bosses and iconic items that have been brought to life in the Diablo III engine.”

It also brings in new Legendary and Set items (these are powerful weapons and armor), Greater Rifts (Diablo 3’s end-game with random levels, monsters, and gear for the ranked Ladder system inside the game), and other improvements. You can read the patch notes in full here.

This is just the first in several anniversary events that Blizzard Entertainment is running in its games to celebrate Diablo. The special Dark Wanderer Tavern Brawl is live in Hearthstone, its digital card game. The Heroes of the Storm MOBA (multiplayer online battle arena, a type of strategy game) and StarCraft 2 (a strategy game) get new Hero Portraits, and the Overwatch first-person team shooter is getting Diablo-themed sprays that you can throw onto surfaces.

Released December 31 in 1996, Diablo is one of Blizzard’s most important franchises. The publisher said Diablo III had racked up more than 30 million copies sold as of 2015, and the series helped make action-RPGs (where you focus more on fighting monsters and collecting loot than exploring a world and a story) a popular genre of video game.

Updated 8:29 p.m. Pacific with a statement from Blizzard Entertainment.