Erlking research arc

The Erlking research arc (story_research_erlking.xml, 40KB) is the HQ research line culminating in the player claiming the Erlking — a Pirate XL battleship (named “Owen” internally in vanilla code).

Script: story_research_erlking.xml
DLC: Pirate
Theme: Discover → approach → board → claim → upgrade Erlking
Erlking ship macro: ship_pir_xl_battleship_01_a_macro (callsign “Owen” — see vanilla debug text)
Factions touched: faction.loanshark (Erlking’s original owner — antagonist), faction.civilian, faction.player

How the arc works

The arc is HQ research-gated. Player advances HQ research until the Erlking research entry unlocks. The arc then triggers:

Research entry selected at HQ
Boso Ta provides commentary on Erlking arrival
Player flies to find the Erlking
Erlking approach detection
Player attempts to board the Erlking
Boarding succeeds → player claims Erlking (with reputation penalty)
Player upgrades Erlking via additional research

Persistent characters

Character	Role
Boso Ta	HQ research scientist + Erlking commentary
Erlking commander	Loanshark NPC, original Erlking owner

Mission entry: “Erlking Research Unlock”

Cue: `Check_Research_Unlocked` → `Research_Entry_Selected`

In-game name: HQ research entry available
Path/Chapter: Erlking research (entry)
Find in game: HQ research menu after sufficient research progress
Prerequisites:
- Pirate DLC installed
- HQ unlocked
- Sufficient HQ research progress
What player encounters:
- Research entry appears in HQ menu
- Player selects entry to commit research effort
- Research countdown begins
Where: Player HQ research menu
Reward: Research underway
Chains to: Research_Finished → Boso_Arrives_Erlking_Remark
Code reference: story_research_erlking.xml Check_Research_Unlocked

Mission entry: “Boso Ta’s Erlking Remark”

Cue: `Boso_Arrives_Erlking_Remark` (+ `_Ref`, `_Wait`)

In-game name: Boso Ta announces Erlking location
Path/Chapter: Erlking research (Discovery)
Find in game: After research finishes
Prerequisites: Research finished
What player encounters:
- Boso Ta arrives at HQ (Boso_Arrives_Erlking_Remark_Wait waits for arrival)
- Boso speaks remark about Erlking (Boso_Arrives_Erlking_Remark_Ref refs LIB_Dialog.Speak_Actor)
- Player learns Erlking’s approximate location
Where: HQ
NPCs involved: Boso Ta
Reward: Erlking location revealed
Chains to: Find_Player_Erlking → Player_Approach_Handler
Code reference: story_research_erlking.xml Boso_Arrives_Erlking_Remark

Mission entry: “Approach the Erlking”

Cue: `Player_Approach_Handler` + `Player_Approach_Ref`

In-game name: Find and approach the Erlking
Path/Chapter: Erlking research (Approach)
Find in game: After Boso’s remark
Prerequisites: Erlking location known
What player encounters:
- Erlking located in specific sector (Loanshark territory)
- Approach mechanics:
  - Player_Approach_Handler — main approach detection
  - Player_Approach_Ref — approach library ref
  - Player_Approach_BattleshipXL_Far_Message (+ _Ref) — message when far from Erlking
  - Player_Next_Approach (+ _Reset) — multiple approach attempts allowed
  - Player_ApproachSignal_StoryCheck — verify story state on approach
- Hostility handling: Player_Hostility_Handler — Erlking is Loanshark-owned, hostile to player
Where: Loanshark territory (Erlking parked location)
NPCs involved: Erlking commander (Loanshark)
Reward: Erlking in range; boarding becomes possible
Chains to: Player_Boarding_Erlking → Boarding_Started
Code reference: story_research_erlking.xml Player_Approach_Handler

Mod conflict risks — Approach

❌ Mods that make Loanshark non-hostile trivialize the approach
❌ Mods that move the Erlking break the trigger location
⚠ Mods that change ApproachObject_Handler affect detection
⚠ Combat mods affect approach feasibility (Erlking is heavily defended)

Mission entry: “Board the Erlking”

Cue: `Player_Boarding_Erlking` + `Boarding_Started` + `Boarding_Successful`

In-game name: Board the Erlking
Path/Chapter: Erlking research (Boarding)
Find in game: After successful approach
Prerequisites: Player in range; boarding fleet prepared
What player encounters:
- Player initiates boarding action against Erlking
- Boarding sequence starts (Boarding_Started)
- If boarding succeeds (Boarding_Successful) → claim path
Where: Erlking location
NPCs involved: Loanshark crew (defenders), player’s boarding marines
Reward: Erlking captured (if successful)
Chains to: Player_Claimed_Erlking → Player_Claimed_Erlking_ReputationDrop
Code reference: story_research_erlking.xml Player_Boarding_Erlking

Mod conflict risks — Boarding

❌ Mods that disable boarding mechanics break the entire arc
❌ Mods that change Loanshark crew strength affect difficulty
⚠ Marine-rebalance mods affect success probability

Mission entry: “Claim Erlking + Reputation Drop”

Cue: `Player_Claimed_Erlking` → `Player_Claimed_Erlking_ReputationDrop`

In-game name: Erlking captured — Loanshark relation drops
Path/Chapter: Erlking research (Aftermath)
Find in game: Auto-fires after successful boarding
What player encounters:
- Erlking now player-owned
- Major Loanshark relation drop (Player_Claimed_Erlking_ReputationDrop)
- Loanshark faction becomes hostile (or more hostile) to player
Reward: Erlking ship + Loanshark relations damaged
Chains to: Player_Erlking_Build_Added (upgrade path)
Code reference: story_research_erlking.xml Player_Claimed_Erlking

Mission entry: “Erlking Upgrade Path”

Cue: `Player_Erlking_Build_Added` → `Player_Erlking_Build_Finished`

In-game name: Erlking upgrade builds
Path/Chapter: Erlking research (Upgrade)
Find in game: After Erlking claimed
Prerequisites: Erlking captured
What player encounters:
- Player can add Erlking upgrade builds at shipyard
  - Player_Erlking_Build_Added — build added
  - Player_Erlking_Build_Cancelled — build cancelled (variation)
  - Player_Erlking_Build_Finished — build complete
- When fully upgraded → Erlking_Fully_Upgraded
Where: Shipyard
NPCs involved: Shipyard manager
Reward: Erlking at max performance
Code reference: story_research_erlking.xml Player_Erlking_Build_*

Save migration

Patch_Userdata — handles userdata patching for save compatibility. Your mod modifying Erlking state must respect this patch.

Path completion summary

A completed Erlking arc yields:

Erlking ship in player fleet (unique XL battleship)
Loanshark faction hostile (relation drop)
Erlking upgraded to maximum specs
Research arc closed

Code references

Concern	Cue
Research unlock	`Check_Research_Unlocked` + `Research_Entry_Selected`
Boso commentary	`Boso_Arrives_Erlking_Remark*`
Erlking approach	`Player_Approach_Handler` + helpers
Hostility handling	`Player_Hostility_Handler`
Boarding	`Boarding_Started` + `Boarding_Successful`
Claim mechanics	`Player_Claimed_Erlking*`
Upgrade path	`Player_Erlking_Build_*`
Save patch	`Patch_Userdata`

Pirate arcs overview
Criminal arc — parallel arc
Welfare 2 research — adjacent research arc

The Erlking is one of X4’s most desired player rewards. A unique XL battleship obtained via heist. Your mod’s interference with boarding mechanics, Loanshark hostility, or HQ research breaks the canonical Erlking acquisition path.