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Good news everyone!

Today we are going to share some details with you on how the galaxy is generated in Stellaris. When discussing this we will also touch on some of the different features of the galaxy and how we try to anticipate what modders will want to do with the galaxy generation in this game and making sure that they will be able to.

When you start a new game you can specify the size and shape of the galaxy as well as the number of (normal) AI empires. Sizes currently range from 200 - 1000 stars. The amount of AI empires only affects how many AI controlled empires that are generated from the start, a lot more will spring into existence during your game. Currently we have three different types of shapes for the galaxy; spiral, elliptical and ring. Spiral galaxies have the stars placed in arms that extend out in a spiral pattern (see “Pinwheel Galaxy”). A spiral galaxy provides an interesting geography, with voids between the arms that might be difficult to pass in a straight line. Elliptical galaxies have the stars placed in a ellipsoidal pattern (see Wikipedia), resulting in a more evenly distributed geography. Ring galaxies have the stars placed in a ring shape around the galaxy core (see “Hoag's Object”). If you play with a ring galaxy you know that other empires have to approach you either clockwise or counterclockwise within the ring, making it easier to cut other empires off from the rest of the galaxy than it is with any other shape. All of these options are of course moddable, both in regards to looks and available options.

Once you are satisfied with your options and decide to start the game, we begin the process of generating the galaxy. When we generate the stars we also decide what class each star should be. Most stars will be star classes with the different spectral types B,A,F,G,K,M. Some star systems can however be more special, like a black hole, pulsar or a neutron star. Every system with a certain star class has a given set of rules that controls how the star system is generated; you will, for example, have a hard time finding habitable planets close to a black hole. All of this is very moddable, you can add your own star classes and remove the existing ones if you want to.

stellaris_dev_diary_03_02_20121005_pulsar.jpg


We also generate some galactic features other than stars. One of these are nebulas. Nebulas are visible on the galaxy map and often contain a bunch of interesting star systems with special rare resources. In a nebula you can expect to encounter some special events and experience certain penalties and bonuses that may impact your decisions when it comes to colonization and fleet movement.

When we generate the contents of each star system we use different system initializers depending on what the system is being used for. If you, for example, were to start as a pre-scripted human you will be placed in our solar system, on Earth. Yes, all of this is moddable also. These initializers allow us to make sure that you, as a player, will always have something interesting to do within a system. They also provide us with ways to create a more balanced start, by being able to affect the content of your star system and systems that are neighboring to yours. It is worth knowing that these initializers have a certain random factor attached to them, so you should never expect the exact same setup between game sessions.

We generate a lot of interesting special content in the different systems, including the ones that no empire is controlling. This content ranges from debris to ships of unknown origin, that could be friendly or not so friendly... Speaking from personal experience when it comes to the “not so friendly” ships, I recommend all players to scout systems before going there with their science ships to survey a potential future colony. It is not fun having your science ship blown out of existence with your most skilled scientist aboard.

stellaris_dev_diary_03_01_20121005_drone_attack_scienceship.jpg


Next week we will talk about the different FTL types.
 
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Thank you for the DD.

If you had a 1000-star galaxy, roughly how many habitable planets would there be? Are systems with multiple habitable planets very rare?

In MoO and many following games, the systems with the best planets tend to be protected by ancient defense systems or some type of space monster. Is the threat level of the potentially-hostile things you might encounter related to the quality of the system?
 
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I will push the undesirables into the black hole.

"Next stop, a place where your kind are accepted"
 
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Will be there events which:
-change star class
-changing the topography of system and its features
-creating new planets or changing the existing ones
 
Will colonized worlds be visually differentiated from inhabited ones by, e.g. lights and such on the night side?
 
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At the moment no, but we have had discussions about it. If we were to allow it I imagine that they will be quite rare.
Sad, since its been estimated that at least 1/3 of the stars in the milky way are binaries. If you were to have really rare systems then I would suggest Trinary/or more systems.
Maybe for an expansion.
 
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very cool. i like the idea that nebulas also have starsystems in them. most games just use nebulas to great barriers. and i wonder what kind of 'resources' are available in the game.
 
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Will it be possible to generate a game with more than one galaxy? If so, will the limit still be 1000 stars in total, or 1000 stars per galaxy?
Or will extragalactic stuff at least get represented through events? (Like the mongol hordes in CK2)

Another great DD, I seriously can't wait for this gem of a game to be released.
 
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Or will extragalactic stuff at least get represented through events? (Like the mongol hordes in CK2)

Another great DD, I seriously can't wait for this gem of a game to be released.

We already kown that there are events such as Endgame Invasion form an other Galaxys
 
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B,A,F,G,K,M

"Oh Be A Fine Girl Kiss Me" - that was the mnemonic we were taught to use when I studied astronomy. But what happened to "O"?
 
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"Oh Be A Fine Girl Kiss Me" - that was the mnemonic we were taught to use when I studied astronomy. But what happened to "O"?

Stars of this type are particularly rare; only 0.00003% of the main sequence are O-type stars.

So if they keep the ratios and you play only 1000-star galaxies, you should see an O-type about once every few thousand games. I guess they could radically boost the likelihood though...
 
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So if they keep the ratios and you play only 1000-star galaxies, you should see an O-type about once every few thousand games. I guess they could radically boost the likelihood though...

The issue with O stars is that their low life span means there is no time for an interesting system forming around it. So O systems would be mostly boring single body systems
 
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The issue with O stars is that their low life span means there is no time for an interesting system forming around it. So O systems would be mostly boring single body systems

With the totally un-boring prospect of massive supernovae . . .
 
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So if they keep the ratios and you play only 1000-star galaxies, you should see an O-type about once every few thousand games. I guess they could radically boost the likelihood though...

I'm guessing they're not planning to keep the ratios, otherwise the overwhelming majority of stars in the universe will be red dwarves
 
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