This is part of an upcoming anniversary patch titled, “Darkening of Tristram”. It will introduce players to the legendary cathedral that started it all and will provide players with up to 16 levels of monster-filled dungeons. It will also feature the four main bosses from the first Diablo game, so prepare to fight the Butcher once more.
However Blizzard expects that this feature will be a “fun” feature and more of a throwback as opposed to legitimately new content and will introduce a “Glorious Retrovision” filter. Basically this will make the game look pixelated and grainy, like as if you were trying to run a 640×480 game on a 1920×1080 display.
Character movement won’t be as fluid and locked to just eight directions, but then again that was how the game was played back in the day so we guess it should at least offer up some fond memories. However if you wanted additional content, Blizzard will also be introducing two new zones to Reaper of Souls in the form of Shrouded Moors and the Temple of the First Born, both which are accessible via Adventure Mode.