Stellar AI

Make Stellaris AI smarter, more strategic, and more fun to play against!

Stellar AI shifts the AI toward a more research-focused playstyle. Research is treated as the AI’s main long-term goal, while industry, energy, and rural production support that focus. The result is an AI that feels more coherent, competitive, and believable without relying on artificial bonuses.

Focus is currently on stability, balance, and maintaining the core design.

Recent Updates

Added reactive economic recovery, stronger strategic resource handling, and improved naval buildup. The AI now responds better to resource pressure, prevents or recovers from strategic resource bottlenecks, and converts strong economies into fleet power more reliably, especially in mid/late game and wartime. The core research-focused design remains unchanged.

• Each empire uses a custom early game expansionist personality for roughly the first 40 years to better tune early expansion. If the empire is at war during this period, it reverts to its original personality. The active personality description can be viewed by hovering over the empire in the diplomacy view.
• The AI invests more intelligently into expansion, infrastructure, and economic setup in the early game instead of overcommitting too early.
• If not under immediate pressure, the AI maintains a lighter opening fleet and transitions more smoothly into midgame military scaling. More aggressive personalities will still invest somewhat more heavily into fleets even in the early game.
• Researcher job priorities have been increased so research labs stay staffed more consistently.
• Specialized research labs on the capital are given stronger priority to support early technological growth.
• Early colony spending has been tuned to reduce cases where the AI overcommits economically.
• Auto-migration has been adjusted so unemployed pops move more quickly.

• The AI maintains a stronger research economy throughout the game, helping it remain technologically competitive into the mid and late game.
• Economic priorities are tuned to better sustain long-term research investment through a more balanced economy, particularly consumer goods and energy production, while also maintaining adequate minerals and food output.
• Research buildings are upgraded more consistently.
• Fleet development scales more reliably with technology and strategic needs.
• The AI reacts more dynamically to stronger neighbors and shifts into higher military investment when needed.
• Military spending and war behavior have been refined to produce more decisive and believable conflicts.
• Reduced Stronghold AI weight and lowered Fortress zone priority to prevent excessive military infrastructure and improve economic efficiency.

Planet specialization has been significantly improved.

• Rural worlds (Generator, Mining, Farming) now prioritize actual districts and zones in use more strongly than theoretical potential.
• Planet modifiers that boost basic resource output now play a bigger role in determining rural specialization.
• Industrial planets transition more reliably into Factory, Forge, or Industrial worlds when real industrial commitment exists.
• Urban worlds are now mainly considered when a planet is not clearly developing toward research, industry, or rural resource production, and when sufficient trade infrastructure exists to justify an urban designation.
• The AI builds more strongly specialized research planets and is less likely to waste designation bonuses on poorly matched colony types.

Planet specialization now relies more heavily on scaling modifiers and specialization flags, updated through an event-driven system when districts or buildings are constructed, upgraded, replaced, or removed. This makes the system easier to maintain, more performance-friendly, and better at adapting to how a planet actually develops.

Stellar AI also uses an AI-only colony type guard. This prevents the AI from selecting clearly inappropriate designations while keeping all colony types available to the player. If a planet later develops toward a different long-term role, the relevant designation becomes available to the AI again and the planet can switch naturally.

Because Stellaris colony designation is influenced by multiple systems, including automation, economic plans, and strategic priorities, a planet may occasionally keep its current role temporarily even if another designation has a higher calculated weight.

Stellaris 4.3 significantly reduced researcher job output. In vanilla, the base output dropped from roughly 6 → 3, alongside a reduction in technology costs.

Stellar AI partially compensates for this by increasing researcher output closer to previous levels (roughly 6 → 5).

This helps maintain a viable research-focused AI that can translate technological progress into stronger economies, more advanced fleets, and a more challenging opponent.

Based on playtesting, the balance works well with around 1.75x tech costs (the setting I usually use), but this can be adjusted to preference.

Hive Minds, Gestalt empires, Ring Worlds, and Habitats remain fully functional, though they received slightly less attention in this update and may still receive further refinement.

For best results, use galaxies with a moderate to high number of colonizable planets.
Recommended range: 0.7×–1× habitable planets.
Logistic Growth Ceiling around 6.5× and Growth Required Scaling around 0.35× generally produce the most consistent results.

Stellar AI is designed to be challenging even without AI bonuses. The recommended difficulty is therefore Ensign, with Captain being a reasonable upper limit for most players.

More experienced players or strong meta builds may still find these settings manageable and may prefer higher difficulties.

Higher difficulties add large statistical bonuses which can make the game harsher without necessarily improving decision-making. Players seeking a tougher challenge can still experiment with higher settings such as Grand Admiral, though these lie outside the intended balance range.

I generally recommend placing Stellar AI near the bottom of your mod load order. This helps ensure that its AI behavior and balance changes are applied consistently.

However, load order can vary depending on your mod setup. If you are using mods whose changes you want to take priority, you may place those below Stellar AI instead. In most cases, keeping Stellar AI toward the end of the list provides the most reliable results.

Not compatible with other AI overhaul mods unless they do not modify economic AI behavior. Stellar AI is also not compatible with mods that modify or add personalities. Large content mods such as Gigastructural Engineering should work in most cases, as long as they do not significantly alter economic AI behavior. Compatibility will be reviewed further over time.

Not compatible with Extra Buildings – All in One (4.3+).
Likely incompatible with mods that modify vanilla buildings. Mods that only add new buildings should generally work.

Please do not reupload or fork Stellar AI without prior permission. Compatibility patches, submods, and integrations are welcome with credit.