Elden Ring Nightreign Setup Guide

Required Software

Elden Ring Nightreign (Steam), no mods or game files need to be modified. The client mostly reads the running game's memory to detect what you're doing; if you have the gate_boss_access option enabled (on by default), it also writes to the game's memory to set the same event flags the game itself uses, revealing secondary Nightlords as you receive their "Access" items. The gate_character_access option (off by default) does the same thing for playable characters instead of Nightlords. It never touches game files on disk.
Archipelago, from the Archipelago releases page, plus this game's .apworld file installed via the Launcher's "Install APWorld" button (or dropped into your Archipelago install's custom_worlds folder if running from source).

Play on a fresh save (or a separate save slot) for your Archipelago run, not one where every Nightlord is already unlocked. With gate_boss_access on (the default), the world assumes it's starting from vanilla's own "only your starting_boss is available" state and reveals the rest as you receive their Access items - if every Nightlord is already unlocked in-game before you connect, there's nothing left for that reveal to do, and the intended progression won't be visible. The same applies to gate_character_access (off by default) and starting_character for playable characters - if you turn it on, start from a save where not every character is already unlocked.

Locked versus Unlocked

You might see that you have all bosses unlocked immediately when you go to launch an expedition. This is expected. The client will only send checks for bosses that you have unlocked. So if you only start with Libra but see every single boss, don't fret. It's working as expected. The other bosses are selectable and you can still do runs on them, but in the eyes of the AP, you have not yet received access and will not send checks. So long as you only do runs on bosses you have unlocked with characters that you have unlocked, then you should be sending checks!

This is exactly how characters work as well.

Something You Received Isn't Unlocked

If a boss or character you've received (including a DLC character like Scholar or Undertaker) isn't selectable, go to the Roundtable Hold and press "Re-apply unlocks" on the client's Unlocks tab, or type /unlock. It doesn't work from the main menu - your save has to be loaded first.

Playing Offline

The game must be launched offline or the client will refuse to open. Selecting the "play offline" option within the menu is insufficient - since this implementation reads and writes data, it can only be play with EAC disabled.

Other Mods