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Stellaris
Stellaris
4.5|Aug 27, 2026
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Stellaris Dev Diary #430 - 4.5 ‘Cygnus’ Development Continues

3/5 Moderate

BETAMajor overhaul to 'Join War' AI logic to prevent snowballing conflicts and new Smelting Processes for Arc Furnaces.

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Key Changes

  • 1Complete overhaul of 'Join War' AI logic to prevent massive snowballing wars
  • 2Arc Furnaces (Tier 3+) can now specialize in Minerals, Alloys, or a mix
  • 3Short-range weapons (Autocannons/Disruptors) removed from Starbase slots
  • 4New notifications for empires joining or leaving active wars
  • 5Nomadic Empires can now negotiate Exclusive Harvesting Rights with settled empires
  • 6Cybernetic pop Job Efficiency increased from 5% to 10%
  • 7Fixed strike craft failing to deal damage due to targeting resets
  • 8Fixed critical crash related to Situation Log transitions
  • 9AI now prioritizes upgrading existing Arkships over building new ones
  • 10Fixed Nascent Stage pre-sapients maturation bug

All Changes

🤝Diplomacy & Features(3)

  • newNomadic Empires: Nomadic and settled empires can negotiate Exclusive Harvesting Rights to share yields without diplomatic penalties.
  • newArc Furnace: Arc Furnaces (Tier 3+) can now switch between Smelting Processes for minerals, alloys, or a mix for an energy cost and 720-day lockout.
  • newObsessional Directive: Empires with Obsessional Directive unlock a unique Commodity Fabrication Smelting Process for Arc Furnaces.

⚖️Balance(8)

  • nerfStarbases: Autocannons, Disruptors, and short-ranged weapons are no longer equippable on Starbases, Orbital Rings, or Deep Space Citadels.
  • buffCybernetic: Cybernetic pop Job Efficiency increased from 5% to 10%.
  • buffCybernetic Luminary: Cybernetic Luminary leader experience penalty reduced from 25% to 10%.
  • nerfOrdnance Engineering: Ordnance Engineering weapon damage per soldier job reduced from 5% to 1%.
  • nerfHive Drones: Limited Cyberization penalty for hive drones doubled to match new efficiency gains.
  • nerfDeep Scanning: Deep Scanning is now less likely to uncover Minor Artifacts if they have already been found in the system.
  • nerfArkships: Reduced arkship harvesting and action modifiers provided by harvester jobs.
  • buffTrade Deposits: Trade deposits now increase the resources gained from harvesting a planet.

🤖AI Behavior(7)

  • changeAI Empires: AI now averages opinions across war sides rather than summing them, reducing the likelihood of joining massive 'dogpile' wars.
  • changeAI Empires: AI empires now consider war size, existing conflicts, and specific grudges against war leaders before joining a war.
  • changeAI Empires: Bribing AI into wars now costs significantly more and scales based on their reluctance.
  • fixGene Clinics: Fixed an AI loop where Gene Clinics were repeatedly upgraded and destroyed based on stability/amenity needs.
  • changeNomadic Empires: Nomad AI now prioritizes upgrading existing Arkships before building new ones.
  • changeAI Empires: AI empires are more willing to grant Harvesting Rights if they have an embassy or Diplomatic Networking tradition.
  • changeDefense Platforms: Automatically generated defense platform designs no longer use short-range weapons like autocannons or disruptors.

🐛Bug Fixes(11)

  • fixPre-sapients: Fixed Nascent Stage pre-sapients failing to mature into adult species.
  • fixStrike Craft: Fixed strike craft losing targets before completing attack runs, resulting in zero damage.
  • fixSituation Log: Fixed a crash occurring when reopening the Situation Log after a situation transition.
  • fixNomadic Empires: Fixed a crash and broken icon when a Nomad empire inherited specialist subjects via subjugation.
  • fixCosmogenesis: Fixed Cosmogenesis exodus ending in defeat if the capital was on the Synaptic Lathe.
  • fixFleets: Fixed an issue where an empire lost all fleets if a single colony was destroyed while others remained.
  • fixSynaptic Lathe: Fixed Synaptic Lathe gaining extra districts from empire-wide modifiers incorrectly.
  • fixTechnology: Fixed Machine Intelligence and Anglers empires almost never drawing food technologies.
  • fixCrystal Asteroids: Crystal asteroids can now properly contain Rare Crystal mining deposits.
  • fixCivics: Fixed Franchising civic and Feudal Society councilor failing to grant intended subject bonuses.
  • fixUI: Resolved multiple issues with missing localization strings and incorrect tooltips across various events and features.

🖥️UI/UX(4)

  • newWar Interface: Added notifications for when empires join or leave a war, including side alignment and war overview shortcuts.
  • changeMegastructures: Megastructure effects are now grouped by scope (Empire, System, or Structure).
  • changeTrade: Trade actions with negotiated values now display those values clearly in offers and ongoing deals.
  • changeGestalt Nodes: Gestalt nodes are now labeled by title alone to reduce naming redundancy.

Summary

Diplomacy & AI Overhaul

This update focuses on stabilizing the 4.5 'Cygnus' Open Beta with a massive rework of the Join War mechanic. AI empires now use averaged opinions and consider war size, existing conflicts, and specific grudges before joining a fight, making grand-scale 'dogpiling' much less common. New notifications also keep players informed when empires join or leave their wars.

Strategic Features

Arc Furnaces receive significant depth with new Smelting Processes at Tier 3, allowing players to specialize output toward minerals, alloys, or a mix. Additionally, Nomadic Empires can now negotiate Exclusive Harvesting Rights with settled empires, facilitating peaceful resource extraction in foreign space.

Balance & Bug Fixes

Combat balance sees a shift as short-range weapons like Autocannons and Disruptors are removed from Starbase and Orbital Ring slots. Critical bug fixes address the 'Nascent Stage' pre-sapient maturation, strike craft targeting issues, and various crashes related to the Situation Log and Nomad inheritance.

← OlderStellaris Dev Diary #429 - Summer Experiments 2026Aug 20, 2026

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