Hello everyone and welcome to yet another development diary for Stellaris! Today, I'll be talking about AI, and not of the robotic kind. I'm talking of course, of the game AI, which is currently being developed by myself and merni who is the dedicated Stellaris AI programmer, while I'm just temporarily on the project to flesh out certain aspects of the AI before launch.

Artificial Personalities
A major challenge when making the Stellaris AI has been the randomized nature of the game. With thousands of different combinations of ethoses and traits, there's a risk that every AI Empire ends up feeling the same to the player, or fall into a very basic categorization of 'aggressive aliens' and 'peaceful aliens'. I as the AI programmer might know that an AI with Fanatic Collectivism makes their decisions differently from with plain old vanilla Collectivism, but it might all look the same to a player who doesn't have this foreknowledge.

In order to address this problem, we've implemented a system of AI Personalities that govern almost every aspect of how they behave, such as who they'll pick a fight with, which trade deals they are interested in and how they budget and utilize the resources available to them. This personality is determined by their ethos, government form and traits, and will be shown to the player when diplomatically interacting with that Empire. To feel recognizeable to the player, all of the personalities are rooted in sci-fi tropes, so that you'll immediately know who the Klingons are to your United Federation of Planets.


Personalities naturally have a bigger impact on diplomacy than anything else - if your goal is to form a Federation, it'll be much easier to do so with an Empire of Federation Builders than a bunch of Ruthless Capitalists, and forget getting Xenophobic Isolationists to agree to any such proposal unless they have a very pressing reason. You can tell how an Empire feels about you from their Attitude, which is primarily driven by opinion, and affects factors such as what diplomatic offers they'll consider and how fair a shake they will give you in trade deals.


In addition to the regular personalities, there is also a special set of personalities for Fallen Empires. Instead of the usual mix of Ethoses, each Fallen Empire has only a single Fanatic Ethos - the single remaining ideal they hold to after centuries of seeing what the galaxy has to offer. This Ethos determines their personality, which in turn affects how they view your actions. For example, a Xenophobic Fallen Empire will want nothing to do with you or anyone else and will be very upset if you start encroaching on their borders, while a Spiritualist Fallen Empire will consider themselves the protectors of the galaxy's holy sites, and will not look kindly on your colonists trampling all over their sacred planets. If you think angering a Fallen Empire is harmless because they won't conquer you - think again. Fallen Empires get a special wargoal to force you to abandon planets, and will be more than happy to cut your upstart species down to size if you don't show sufficient respect for your elders.


Threats and Rivals
So what then, is a pressing reason for an AI to go against their personality? Well, one such reason is Threat. Threat is a mechanic somewhat similar to Aggressive Expansion in Europa Universalis 4. Conquering planets, subjugating other Empires and destroying space installations will generate Threat towards other Empires. The amount of Threat generated depends both on how far away the Empire is from what's happening and on their Personality. Xenophobic Isolationists won't care if you're purging aliens half a galaxy away, but if all the planets around them being swallowed up by an expanionistic Empire, they'll definitely take note. Empires that are threatened by the same aggressor will get an opinion boost towards each other, and will be more likely to join in Alliances and Federations - if you go on a rampage, you may find the rest of the Galaxy uniting to take you down, and while Threat decays naturally over time, there's no guarantee that the alliances formed by your imperialism will break up even if you take a timeout from conquering... so expand with care.

Another feature borrowed from EU4 to drive AI behaviour is Rivals. Any independent Empire that are you not allied to can be declared a Rival, up to a maximum of 3 Rivals at the same time. Having an Empire as a Rival will give you a monthly increase of Influence, with the amount gained based on how powerful they are relative to yourself - having a far weaker Empire as your antagonist will not overly impress your population. It is further modified by Ethos, with Militarist Empires benefitting significantly more from Rivalries than Pacifist ones (but paying more influence to be part of an Alliance). Naturally, Empires won't be particularly happy about declaring a Rival, and are pretty likely to Rival you right back. Having a Rival will improve relations with their enemies and worsen relations with their friends, so the Rivalry system will act as a primary driver of conflict and alliance in the galaxy.


AI Economics
Finally, I wanted to cover the topic of the AI's bookkeeping. While it may be far less exciting and far less visible to the player than its diplomatic behaviour, having solid economics is one of our biggest priorities for the Stellaris AI, for multiple reasons. Firstly, so that the AI is able to compete reasonably with the player without resorting to outright cheating. True, the AI will never be as good as an experienced player, but there is a big difference between the player being able to outproduce one AI Empire and the player being able to outproduce five of them together. Secondly, because of the Sector mechanic that was covered in DD 21, the AI will actively be making construction and management decisions on the player's planets, and while - again - it will never be as good as an experienced player making the decisions themselves, it needs to be good enough that the player doesn't feel like the AI is actively sabotaging their Empire.

In order to accomplish all this, a huge amount of time has been put into the AI's budgeting system. Every single mineral and energy credit that the AI takes in is earmarked for a particular budget post such as navies or new colonies, with the division between the posts being set according to the AI's personality and what it needs at the time. The AI is only permitted to spend appropriately budgeted resources, so it'll never fail to establish new colonies because it's too busy constructing buildings on its planet, or miss building a navy because mining stations are eating up its entire mineral income. In times of dire need, it can move resources from one budget post to another - if it's at war and its navy gets destroyed, expect it to pour every last mineral into building a new one.

When making decisions about what to construct, the AI looks primarily at what resources it has a critical need for (such as Energy if it's running a deficit), secondarily at what resources it's not producing a lot of compared to what it expects an Empire of its size to produce, and lastly at whatever it deems useful enough for the mineral investment. Sectors have additional logic to ensure they produce more of the resource you've set them to focus on, so an Energy sector will naturally overproduce Energy - you told it to, after all.

Hello everyone and welcome to yet another development diary for Stellaris! Today, I'll be talking about AI, and not of the robotic kind. I'm talking of course, of the game AI, which is currently being developed by myself and merni who is the dedicated Stellaris AI programmer, while I'm just temporarily on the project to flesh out certain aspects of the AI before launch.

Artificial Personalities
A major challenge when making the Stellaris AI has been the randomized nature of the game. With thousands of different combinations of ethoses and traits, there's a risk that every AI Empire ends up feeling the same to the player, or fall into a very basic categorization of 'aggressive aliens' and 'peaceful aliens'. I as the AI programmer might know that an AI with Fanatic Collectivism makes their decisions differently from with plain old vanilla Collectivism, but it might all look the same to a player who doesn't have this foreknowledge.

In order to address this problem, we've implemented a system of AI Personalities that govern almost every aspect of how they behave, such as who they'll pick a fight with, which trade deals they are interested in and how they budget and utilize the resources available to them. This personality is determined by their ethos, government form and traits, and will be shown to the player when diplomatically interacting with that Empire. To feel recognizeable to the player, all of the personalities are rooted in sci-fi tropes, so that you'll immediately know who the Klingons are to your United Federation of Planets.


Personalities naturally have a bigger impact on diplomacy than anything else - if your goal is to form a Federation, it'll be much easier to do so with an Empire of Federation Builders than a bunch of Ruthless Capitalists, and forget getting Xenophobic Isolationists to agree to any such proposal unless they have a very pressing reason. You can tell how an Empire feels about you from their Attitude, which is primarily driven by opinion, and affects factors such as what diplomatic offers they'll consider and how fair a shake they will give you in trade deals.


In addition to the regular personalities, there is also a special set of personalities for Fallen Empires. Instead of the usual mix of Ethoses, each Fallen Empire has only a single Fanatic Ethos - the single remaining ideal they hold to after centuries of seeing what the galaxy has to offer. This Ethos determines their personality, which in turn affects how they view your actions. For example, a Xenophobic Fallen Empire will want nothing to do with you or anyone else and will be very upset if you start encroaching on their borders, while a Spiritualist Fallen Empire will consider themselves the protectors of the galaxy's holy sites, and will not look kindly on your colonists trampling all over their sacred planets. If you think angering a Fallen Empire is harmless because they won't conquer you - think again. Fallen Empires get a special wargoal to force you to abandon planets, and will be more than happy to cut your upstart species down to size if you don't show sufficient respect for your elders.


Threats and Rivals
So what then, is a pressing reason for an AI to go against their personality? Well, one such reason is Threat. Threat is a mechanic somewhat similar to Aggressive Expansion in Europa Universalis 4. Conquering planets, subjugating other Empires and destroying space installations will generate Threat towards other Empires. The amount of Threat generated depends both on how far away the Empire is from what's happening and on their Personality. Xenophobic Isolationists won't care if you're purging aliens half a galaxy away, but if all the planets around them being swallowed up by an expanionistic Empire, they'll definitely take note. Empires that are threatened by the same aggressor will get an opinion boost towards each other, and will be more likely to join in Alliances and Federations - if you go on a rampage, you may find the rest of the Galaxy uniting to take you down, and while Threat decays naturally over time, there's no guarantee that the alliances formed by your imperialism will break up even if you take a timeout from conquering... so expand with care.

Another feature borrowed from EU4 to drive AI behaviour is Rivals. Any independent Empire that are you not allied to can be declared a Rival, up to a maximum of 3 Rivals at the same time. Having an Empire as a Rival will give you a monthly increase of Influence, with the amount gained based on how powerful they are relative to yourself - having a far weaker Empire as your antagonist will not overly impress your population. It is further modified by Ethos, with Militarist Empires benefitting significantly more from Rivalries than Pacifist ones (but paying more influence to be part of an Alliance). Naturally, Empires won't be particularly happy about declaring a Rival, and are pretty likely to Rival you right back. Having a Rival will improve relations with their enemies and worsen relations with their friends, so the Rivalry system will act as a primary driver of conflict and alliance in the galaxy.


AI Economics
Finally, I wanted to cover the topic of the AI's bookkeeping. While it may be far less exciting and far less visible to the player than its diplomatic behaviour, having solid economics is one of our biggest priorities for the Stellaris AI, for multiple reasons. Firstly, so that the AI is able to compete reasonably with the player without resorting to outright cheating. True, the AI will never be as good as an experienced player, but there is a big difference between the player being able to outproduce one AI Empire and the player being able to outproduce five of them together. Secondly, because of the Sector mechanic that was covered in DD 21, the AI will actively be making construction and management decisions on the player's planets, and while - again - it will never be as good as an experienced player making the decisions themselves, it needs to be good enough that the player doesn't feel like the AI is actively sabotaging their Empire.

In order to accomplish all this, a huge amount of time has been put into the AI's budgeting system. Every single mineral and energy credit that the AI takes in is earmarked for a particular budget post such as navies or new colonies, with the division between the posts being set according to the AI's personality and what it needs at the time. The AI is only permitted to spend appropriately budgeted resources, so it'll never fail to establish new colonies because it's too busy constructing buildings on its planet, or miss building a navy because mining stations are eating up its entire mineral income. In times of dire need, it can move resources from one budget post to another - if it's at war and its navy gets destroyed, expect it to pour every last mineral into building a new one.

When making decisions about what to construct, the AI looks primarily at what resources it has a critical need for (such as Energy if it's running a deficit), secondarily at what resources it's not producing a lot of compared to what it expects an Empire of its size to produce, and lastly at whatever it deems useful enough for the mineral investment. Sectors have additional logic to ensure they produce more of the resource you've set them to focus on, so an Energy sector will naturally overproduce Energy - you told it to, after all.

Good news everyone!

Today’s Dev Diary will be about Multiplayer and what makes it so great in Stellaris.

Let's start with the basics. Players are able to host games with 32 player designed empires and optionally, several extra randomized AI empires. If you have a new person who would like to join an ongoing campaign they can hotjoin into an already existing empire. This also allows the players to leave or take a break from the ongoing multiplayer campaign and leave their empire in the capable hands of the AI. The host may also choose to host a multiplayer game from a save game allowing players to play grand campaigns lasting several weeks.



One of our longstanding issues with multiplayer is that clients desynchronize, which is usually solved by having the host rehost the game, but this can be quite a menace when playing multiplayer with 20+ people, so we’ve decided that this is an issue we should prioritize higher in Stellaris. Thanks to persistent testing and fixing of out-of-syncs as soon as they happen, we’ve managed to make Stellaris our most stable multiplayer experience yet, allowing us to run stable multiplayer with up to and probably more than 32 players. We test our multiplayer stability weekly by playing multiplayer with our betas and the developers on the project, and it’s loads of fun.



We’ve designed Stellaris with a couple of things which affects the multiplayer experience which you might want to know.

One of them is that empires have a relationship value of other empires, but the value doesn’t decide the options a player can take against another empire but decides the responses AI controlled countries gives to your requests, demands and offers.

Another thing which Stellaris has that our other grand strategy games don’t is a symmetrical and randomized start, this means that in a multiplayer game everyone starts on more or less equal terms. This makes the game, in our experience, more competitive and a lot of fun. Will you be able to claim ownership of that specifically resource rich system before your neighbor? Or should you enter an alliance to stop a specific neighbor from expanding in your direction?

One more thing which affects the multiplayer experience on an early stage is that players are anonymous until you have established communications with their empires, making you unable to know whether the first aliens you meet will be your greatest allies or your worst enemies.

Next week is all about the AI.

Read original post with larger images

Useful links
Official Website
Stellaris Wiki
Developer Diary Archives

Good news everyone!

Today’s Dev Diary will be about Multiplayer and what makes it so great in Stellaris.

Let's start with the basics. Players are able to host games with 32 player designed empires and optionally, several extra randomized AI empires. If you have a new person who would like to join an ongoing campaign they can hotjoin into an already existing empire. This also allows the players to leave or take a break from the ongoing multiplayer campaign and leave their empire in the capable hands of the AI. The host may also choose to host a multiplayer game from a save game allowing players to play grand campaigns lasting several weeks.



One of our longstanding issues with multiplayer is that clients desynchronize, which is usually solved by having the host rehost the game, but this can be quite a menace when playing multiplayer with 20+ people, so we’ve decided that this is an issue we should prioritize higher in Stellaris. Thanks to persistent testing and fixing of out-of-syncs as soon as they happen, we’ve managed to make Stellaris our most stable multiplayer experience yet, allowing us to run stable multiplayer with up to and probably more than 32 players. We test our multiplayer stability weekly by playing multiplayer with our betas and the developers on the project, and it’s loads of fun.



We’ve designed Stellaris with a couple of things which affects the multiplayer experience which you might want to know.

One of them is that empires have a relationship value of other empires, but the value doesn’t decide the options a player can take against another empire but decides the responses AI controlled countries gives to your requests, demands and offers.

Another thing which Stellaris has that our other grand strategy games don’t is a symmetrical and randomized start, this means that in a multiplayer game everyone starts on more or less equal terms. This makes the game, in our experience, more competitive and a lot of fun. Will you be able to claim ownership of that specifically resource rich system before your neighbor? Or should you enter an alliance to stop a specific neighbor from expanding in your direction?

One more thing which affects the multiplayer experience on an early stage is that players are anonymous until you have established communications with their empires, making you unable to know whether the first aliens you meet will be your greatest allies or your worst enemies.

Next week is all about the AI.

Read original post with larger images

Useful links
Official Website
Stellaris Wiki
Developer Diary Archives

Greetings fellow gamers!

The topic for today is “Alliances and Federations”. Now, we have modelled alliances quite differently in most of our games. In Crusader Kings II, for example, alliances are bilateral, and allies are (since the last patch) automatically dragged into wars with no option of opting out and breaking the alliance. In Europa Universalis IV, alliances are also bilateral, but you can decline a “Call to Arms” at the cost of Prestige. In Stellaris, alliances are multilateral (they can have any number of members, not just two), and are thus more like NATO and less like the complex web of mutual agreements that existed at the outbreak of the Great War. This means that members of an alliance need a greater say in matters that concern the entire alliance, notable declarations of war (and some things are simply not allowed if you are an alliance member, such as guarantees of independence.)

If I am a member of an alliance in Stellaris and I want to declare a war, all the other members of the alliance need to approve. This ties back to what I talked about in the dev diary two weeks ago; if the goals I declare with the war are only beneficial to myself, my allies are of course less likely to approve. Therefore, I will likely have to dicker with the war goals in order to satisfy all of my allies (depending on their opinions and strategic concerns, naturally.) Of course, members can always just leave an alliance (while at peace) if it won’t permit them to achieve their goals.



If an alliance works well, however, the members can instead choose to deepen their cooperation and form a Federation. There are pros and cons to this choice. Alliances can be paralyzed by vetoes from the member states, but a Federation is governed by a single President who has the power to act with impunity. On the other hand, the presidency rotates between the member states, so for long periods members will have little control over their foreign policy. Federation members also share victory, which might be a problem for certain types of players…

Another interesting feature of Federations is that they have a special joint space navy in addition to the forces of the separate member empires. The Federation president gets to design these ship templates using all the best technologies of all the member empires. The president also gets to control these fleets, of course. As a rule of thumb, several fairly equally matched empires might want to form a Federation, especially in the face of aggressive, significantly larger neighbors, but it might not be the best idea for empires who are dominant in their own right. Of course, there is also an element of role-playing to the choice…



That’s all for now. Next week’s topic is Multiplayer!

Read the original post with larger images...

Useful links
Official Website
Stellaris Wiki
Developer Diary Archives

Greetings fellow gamers!

The topic for today is “Alliances and Federations”. Now, we have modelled alliances quite differently in most of our games. In Crusader Kings II, for example, alliances are bilateral, and allies are (since the last patch) automatically dragged into wars with no option of opting out and breaking the alliance. In Europa Universalis IV, alliances are also bilateral, but you can decline a “Call to Arms” at the cost of Prestige. In Stellaris, alliances are multilateral (they can have any number of members, not just two), and are thus more like NATO and less like the complex web of mutual agreements that existed at the outbreak of the Great War. This means that members of an alliance need a greater say in matters that concern the entire alliance, notable declarations of war (and some things are simply not allowed if you are an alliance member, such as guarantees of independence.)

If I am a member of an alliance in Stellaris and I want to declare a war, all the other members of the alliance need to approve. This ties back to what I talked about in the dev diary two weeks ago; if the goals I declare with the war are only beneficial to myself, my allies are of course less likely to approve. Therefore, I will likely have to dicker with the war goals in order to satisfy all of my allies (depending on their opinions and strategic concerns, naturally.) Of course, members can always just leave an alliance (while at peace) if it won’t permit them to achieve their goals.



If an alliance works well, however, the members can instead choose to deepen their cooperation and form a Federation. There are pros and cons to this choice. Alliances can be paralyzed by vetoes from the member states, but a Federation is governed by a single President who has the power to act with impunity. On the other hand, the presidency rotates between the member states, so for long periods members will have little control over their foreign policy. Federation members also share victory, which might be a problem for certain types of players…

Another interesting feature of Federations is that they have a special joint space navy in addition to the forces of the separate member empires. The Federation president gets to design these ship templates using all the best technologies of all the member empires. The president also gets to control these fleets, of course. As a rule of thumb, several fairly equally matched empires might want to form a Federation, especially in the face of aggressive, significantly larger neighbors, but it might not be the best idea for empires who are dominant in their own right. Of course, there is also an element of role-playing to the choice…



That’s all for now. Next week’s topic is Multiplayer!

Read the original post with larger images...

Useful links
Official Website
Stellaris Wiki
Developer Diary Archives

Hi again folks!

Today I am going to talk about one of the great pitfalls of strategy game design; dull micromanagement. That is, features which require too much player attention. The trick, of course, is determining how much is “too much”, but it’s useful to consider how central the feature is to the core gameplay, how well it scales between small and large states, and how repetitive it gets with time.

In Stellaris, one feature which risked causing bad micromanagement was the planetary tile system; assigning Pops to tiles and deciding which buildings should go where. It is a fairly central feature and it is fun to use… but if you had to worry about 20, 50 or more planets, it would scale poorly. The obvious solution to this type of scaling issue is automation; you can let the AI handle it for you. This is indeed what we did in Stellaris, but not in a “traditional” fashion... Instead, we opted for something a little bit more akin to the vassals in Crusader Kings through something we call Administrative Sectors.



A Sector is an administrative region under the control of a Sector Governor. You can control a few planets directly (your “core worlds”), but once you go past the limit, you will start suffering penalties to your Influence as well as Empire-wide income. The exact limit for how many planets you can control directly depends on various factors, like your government type and technologies, but, as with the “Demesne Limit” in Crusader Kings II, it will never be a huge number. At this point, it is best to start dividing your territory into Sectors. You can decide the Sector capital and which planets should belong to it (but they must all be connected to the capital, i.e. form one cohesive sub-region.) You are also allowed to name your Sectors, for fun.

Unlike proper Vassals, Sectors remain an integrated part of your Empire, but they will handle development of planets and the construction of mining stations within their region for you. You can give them a focus (Industry, Research, etc), an infusion of Minerals or Energy Credits to help them along, and decide if you want to tax them for Minerals and Energy Credits. Sectors do not possess any military fleets of their own, nor do they perform research (they have access to the same technologies you do, and their research output is all given to you.)



While Sectors and Sector Governors cannot demand more autonomy, or directly rise up in revolt (things I’d love to explore in an expansion), over time their population tends to diverge ideologically from that of the regime, and create their own identity. Like-minded Pops will tend to migrate there if allowed to. In the same way, aliens of the same species will also tend to coalesce in the same Sectors. Thus, when Factions form, they will often tend to have their main seat of power in a specific Sector. And Factions can demand autonomy and achieve independence. However, this is something that warrants its own dev diary...

That’s all he wrote folks. This time. Next week, I plan to talk about Alliances and Federations!

Read original post with larger images

Useful links
Official Website
Stellaris Wiki
Developer Diary Archives

Hi again folks!

Today I am going to talk about one of the great pitfalls of strategy game design; dull micromanagement. That is, features which require too much player attention. The trick, of course, is determining how much is “too much”, but it’s useful to consider how central the feature is to the core gameplay, how well it scales between small and large states, and how repetitive it gets with time.

In Stellaris, one feature which risked causing bad micromanagement was the planetary tile system; assigning Pops to tiles and deciding which buildings should go where. It is a fairly central feature and it is fun to use… but if you had to worry about 20, 50 or more planets, it would scale poorly. The obvious solution to this type of scaling issue is automation; you can let the AI handle it for you. This is indeed what we did in Stellaris, but not in a “traditional” fashion... Instead, we opted for something a little bit more akin to the vassals in Crusader Kings through something we call Administrative Sectors.



A Sector is an administrative region under the control of a Sector Governor. You can control a few planets directly (your “core worlds”), but once you go past the limit, you will start suffering penalties to your Influence as well as Empire-wide income. The exact limit for how many planets you can control directly depends on various factors, like your government type and technologies, but, as with the “Demesne Limit” in Crusader Kings II, it will never be a huge number. At this point, it is best to start dividing your territory into Sectors. You can decide the Sector capital and which planets should belong to it (but they must all be connected to the capital, i.e. form one cohesive sub-region.) You are also allowed to name your Sectors, for fun.

Unlike proper Vassals, Sectors remain an integrated part of your Empire, but they will handle development of planets and the construction of mining stations within their region for you. You can give them a focus (Industry, Research, etc), an infusion of Minerals or Energy Credits to help them along, and decide if you want to tax them for Minerals and Energy Credits. Sectors do not possess any military fleets of their own, nor do they perform research (they have access to the same technologies you do, and their research output is all given to you.)



While Sectors and Sector Governors cannot demand more autonomy, or directly rise up in revolt (things I’d love to explore in an expansion), over time their population tends to diverge ideologically from that of the regime, and create their own identity. Like-minded Pops will tend to migrate there if allowed to. In the same way, aliens of the same species will also tend to coalesce in the same Sectors. Thus, when Factions form, they will often tend to have their main seat of power in a specific Sector. And Factions can demand autonomy and achieve independence. However, this is something that warrants its own dev diary...

That’s all he wrote folks. This time. Next week, I plan to talk about Alliances and Federations!

Read original post with larger images

Useful links
Official Website
Stellaris Wiki
Developer Diary Archives