The strangest part of talking about Old School RuneScape is the understanding that while this is technically RuneScape as it was back in September 2007, that the game is slowly moving in a direction away from both its original design and the actual progression of the main game. Features like the Nightmare Zone are particularly interested because the idea of fighting boss monsters from quests is something that has been requested in RuneScape for years, at least as long as I’ve been playing, so this will be one of the first additional pieces of content that will go into Old School RuneScape while still being completely ignored on the live game.
So Nightmare Zone is closer to completion and Jagex have been working out details on how to deal with creatures that require special items to creatures that almost require special items, NPCs that really only function properly in their own environments, etc. As a compromise, the game provides various items that are required but would not otherwise even be obtainable by the player, while other items are simply removed from the equation. Rewards are still being worked on, since the community shot down every single pitch in the related content poll.
(Source: Dev Blog)
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