How Regions Unlock (Progression)

Dungeon Settlers opens its regions in a fixed chain, and the unlock is derived, not stored. Every time a campaign loads, the game resets every region to locked, then walks the regions whose IsCleared flag is set and re-opens each cleared region's neighbour (OpenAdjacentRegion). Clearing region N is the one and only thing that opens region N+1:

Veil of Silence -> Festering Burrow -> Abandoned Mine -> Forgotten Abyss -> Dead Swamp -> Tower of Apocalypse

Only the first two regions have real content; the rest are placeholders (see the Gated Content page).

What counts as clearing a region

Each region names a clear boss in the constant GAMESYSTEM_Dungeon_UnitForClearRegion - kill it and the region flips to cleared, which immediately unlocks the next region on load. The dev comment on that constant is explicit: if the slot is NULL, the boss doesn't exist and the region won't unlock the next one. In the current demo data only slot 0 is filled - Veil of Silence's clear boss is the Giant Stone Golem - and every other slot is NULL.

The demo truth: the chain is broken on purpose

In the stock demo the Golem fight can never happen, so the chain never advances past region 0:

• The boss room (DUNGEONROOM_VeilSilence_Boss_GiantStoneGolem) only generates on dungeon phase 5 (AvailablePhases = [5]).
• Which phase each floor uses comes from a phase table. The default table (GAMESYSTEM_Dungeon_Floor_Phase_Division = [2, 4, 5]) reaches phase 5 on the last floor - but Veil of Silence carries its own override, GAMESYSTEM_Dungeon_Floor_Phase_Division_Veil_Silence = [1, 2, 3, 3, 4], which caps at phase 4. Floor 5 generates as a phase-4 floor, the phase-5-only boss room is never eligible, and the Golem never spawns - so Veil of Silence can never be cleared by combat and Festering Burrow is unreachable in the stock demo.
• As a second lock, the demo binary special-cases region 1: even a cleared Veil of Silence refuses to open Festering Burrow (the unlock loop, the available-region list and the region-request sanitizer all carry hardcoded region-1 exceptions).

Instead, the demo auto-completes: once you descend deep enough (a demo-only resolver checks your floor number, firing on the deepest floors) Veil of Silence is marked cleared and the "successful expedition" and wishlist screens appear - no boss kill required, and no region unlocked.

What the full game presumably does is simply not cap the override (the default [2, 4, 5] division already behaves this way): the last floor becomes the phase-5 boss floor, the boss generates, and killing it clears the region and opens the next one.

Main quest vs region clear

Finishing the main story is a separate axis from clearing regions. The Crawling Doom main chain (Main0-8) ends with killing the Red Monster Rat - an elite monster, not the region's clear boss. Completing it finishes the scenario's story but does not clear Veil of Silence and does not unlock Festering Burrow. Only the region's clear boss (or the demo's auto-clear) flips the IsCleared flag that drives the unlock chain. See Quests.

(For save editors: because the unlock is re-derived on every load, editing a region's IsLocked field does nothing on current builds; the only save-side lever is the previous region's IsCleared - and on the stock demo binary even that is blocked for Festering Burrow. Older ~B.0.2.x builds stored the unlock instead, where IsLocked edits did work. See Save Files.)