update · September 17, 2026
Stellaris Update 4.5 Cygnus Preliminary Patch Notes
Stellaris update 4.5 Cygnus introduces a major overhaul to pop groups, removing division by ethics and factions while overhauling ship design policies and breaking save compatibility. The release also packs hundreds of bug fixes alongside extensive balance adjustments for nomad empires and cyberization.
The Stellaris 4.5 Cygnus update arrives with a complete restructuring of how pop groups, factions, and ethics work alongside a massive wave of bug fixes and balance changes. Because pop groups are no longer strictly divided by ethics or factions, save game compatibility is broken. Players should expect a completely fresh ecosystem for tracking demographic attraction and political alignment.
Demographics and Faction Overhaul
Pop groups are no longer segregated by ethics or factions. Instead, individual pop groups hold a calculated percentage belonging to each ethic or faction. Ethics and factions now appear directly on pop group entries in the planetary management UI, with detailed modifier breakdowns available by holding Alt. Pops shift ethics and convert to factions more frequently, while faction randomization logic and attraction factors have received a comprehensive pass. Factions with identical ethics can now be promoted or suppressed independently, and factions lacking eligible members are destroyed after a delay.
Ship Design and Fleet Policies
Empires gain finer control over automated ship designs through new fleet doctrines and preference policies. Players can assign a Fleet Doctrine policy choosing from six tactics to dictate automated layouts and auto-complete behavior. Additional Weapon Preference and Defense Preference policies guide automated construction and research, while distinct starbase preference policies allow station loadouts to diverge from fleet standards. Furthermore, starbase, orbital ring, and waystation weapon modules are now weapon-type-specific and tied directly to their corresponding technologies.
Federation and Nomad Adjustments
Federations can now enact laws providing automatic, free commercial pacts, wayline pacts, or research agreements among members. Trade League federations automatically grant commercial and wayline pacts between members. Nomadic empires gain compatibility with Cosmogenesis, Storm Chasers, and specific patron accords like the Composer of Strands and Whisperers in the Void. Additionally, regular empires can now cancel accepted contracts after 20 years.
Balance and Progression Tweaks
Cybernetic traits now grant +10% Job Efficiency, up from 5%, though the limited cyberization penalty for hive drones doubles to match. Consecrated World mechanics are completely reworked, granting deterministic empire-wide bonuses to unity, amenities, and spiritualist ethics attraction that scale with the count of consecrated worlds. Biological ships now consume food instead of energy during deficits, and strike craft and missile defensive modifiers now properly affect units launched from starbases and defense platforms.
Bug Fixes and Quality of Life
The update resolves an issue where pop and country ethics were progressively wiped across galaxies. Auto-complete ship designs no longer leave weapon or strike craft slots empty after upgrades, and carrier-computer ships now correctly position themselves using the longer of their weapon or strike craft range. The Dyson Swarm and Arc Furnace system finders have also been overhauled to show accurate, unhindered resource deposits.
Why this patch matters
Cygnus alters foundational Stellaris systems, trading old demographic restrictions for a fluid percentage-based tracking system while delivering long-requested automation controls and a record number of bug fixes.