I like there being neutral races, because it offers some potentially interesting choices with respect to how to annex them (propaganda, economic takeovers, slow immigration of loyal races, religious conversion...)

I see, thanks, that's the feedback I'm looking for (what is fun and what to keep).

It sounds like you're making a distinction between the race and the state

Well... yes... or maybe. Multiracial empire is one of my ideas. But I feel I'm missing something very important here and that it is not the core of the game.

Maybe let's look at it from the point of view of planets & gameplay ignoring the races for a moment.

In that game you should claim like 1/3 of the map (the central part around your home world) very fast and very early, it's like the core of your empire that stays loyal to you most of the time. Then the next 1/3 should be claimable with a modest effort (propaganda, diplomacy, culture, economic take over). And the last 1/3 should be some sort of frontier/outskirts with planets resistant to joining, the breeding ground of pirates, separatists, rebels, strange & dangerous aliens, the use of force would be primary form of conquest in that part.

Then some disaster comes (in forms of very aggressive aliens) and they start conquering/annihilating planets (no matter who owns it) and the player try to stops them in a tower defence style (so neutral planets are useful as an expendable cannon fodder that slows enemy without any negative effect to us (it's not our citizens/factories that are annihilated)).

Then there is some internal separatists uprising and some of our planets turn rebels and want to leave the empire which we need to stop as well.

That's how it should look like from the gameplay point of view (I don't know how/where races falls in here...)

Colonization mechanic - it should be fast at the beginning, like 1 planet per turn, and the immigration to new planets should be fast as well (and growth rate on empty planets too blazing fast - until they reach modest numbers). Let's say your empire colonizes one planet each turn automaticaly. They go by the distance from your capital. You can also click a planet and set "colonize", it will be colonized first or click "do not colonize" and it will be never colonized (so you only prioritize or disallow colonization). The neutral races could colonize separately.

Once a planet is colonized it gets an "empire join check" and it either joins the empire instantly or not (if it was colonized by citizens of your empire you get a +50% bonus to instant joining).

Or maybe make it a single race empire?

Like: you are Terrans, all aliens are hostile/weird/not to be negotiated with.

You start with the single planet in the center then automatic colonization starts. There are two kinds of colonization: "official" done by corporations with the intent to stay in the empire, always nearby planets and "private" with the intent to set a far, far away frontier planet your independent home with own government.

So you are all the same race, just the population pararerly colonizes inside the empire and outside of it.

Then the population migrates as they see fit (you have no/low control over it).

Fauna & flora - instead of the "40 random races" there could be randomly generated fauna & flora on planets, some very hostile/dangerous. The thing is once someone colonizes the planet the fauna can travel too (there are always some idiots that take take their pet Xenozaur to another planet) and you some times don't want these to spread around.

Since you have no control over neutral planets it might become a breeding ground for these nasty parasites/diseases and you might want to introduce a ban/restriction to travel to planets outside your empire (or quarantine them, or simply bombard from the orbit as the last resort).

Hmmm, it might be interesting too I suppose...

After agonizing thinking (both solutions had merit & tastiness) I decided to go for a single race empire (terrans) :) The population spreads on the galaxy on their own (frequently choosing to stay independent) and one of your goals would be to unify them (make join the empire).

Also, I would probably add more hostile alien races.

Example of (more) hostiles:

- colonization of methane breathers - they come from one side of the map, they do not strive to conquer the galaxy but take over planets one by one (they prefer empty planets - avoid conflict), the thing is they terraform these planets making them useless (unless reterraformed), so it is the player who needs to be aggressive if he wants to preserve the planets for future.

- colonization of methane breathers -

This idea is where it's at. I love this. It appeals to my longing for truly alien aliens, otherworldly entities that aren't merely humanoids with brightly colored skin or bumpy foreheads. I also think it is a great idea to have an opponent driven by unique motivations like a methane atmosphere.

- colonization of methane breathers -

This idea is where it's at. I love this. It appeals to my longing for truly alien aliens, otherworldly entities that aren't merely humanoids with brightly colored skin or bumpy foreheads. I also think it is a great idea to have an opponent driven by unique motivations like a methane atmosphere.

The (current ) plan is like that.

* You are Terrans, some of your people belong to the Empire (good) and some stay independent (bad) or are inside the empire but rebel (bad).

* Then there are non humanoid races, all hostile (in various degrees).

* Humanoid aliens??? I hesitate about them, if they exist they were to be neutral but could not join the empire. So I'm not really sure they make sense at all...

About aliens.

The aliens do not play the game. They do not try to stop the player, they just go around and do their stuff. They have their own objectives (which is not "winning the game"). Like parasictic symbiots want to have an enjoyable mating season once every 100 turns and that's it, they don't even understand this "conquest the galaxy" thing

There is also "everyone for himself" which means the player might want to preserve some alien race and use as a "cannon fooder" to stop other aliens.

List of aliens:

* aliens from another dimension - the most dangerous ones, they will always come eventually and an important part of the game is to become strong enough for their arrival. They spawn at the trans-dimensional portals at the very edge of the galaxy and then go stright for the player's capital. They do not colonize or conquer, just anihilate all life they encounter.

* parasitic symbiots - they live in one planet (insane defences) and once every 100 turns go on a breeding spree. They colonize & conquer nearby planets (they never kill all the population, but the loses are very high). Then, after 30-50 turns they die out and/or come back to their home planet and hibernate. And the cycle repeats

* methane breathers - come from one side of the galaxy and colonize planets, first they "xenoform" the planet making it unusable for the player (they try to avoid conflict and first go for uninhabited planets).

* the hive - insectoids, barely sentient, they have very slow and expensive colonization. Actually they have no ships, but launch new "hive clusters" from their planet to the next. The have zero space warfare capabilities, but on the ground they are formidable opponents. The trick is the player can "plant" them (steal one of their hive clusters and transport it to some distant planet where they start to live), which might be useful to stop other aliens (won't work against methane breathers since they will xenomorph the planet killing them all without a fight).

* the elders - a race in decline (negative breeding rate, they most likely will extinct somewhere in the mid game), they used to rule the galaxy, now they are dying out and are passive and not interested in anything. They are quite powerful. When they extinct the player can scavenge their technologies and assets (or earlier ).

List of other threats:

* pirates - they have a base somewhere and outposts, can't be eradicated since they will respawn from nothing eventually (they are Terrans). They go around and plunder planets or force them to pay tribute. They target only other Terran planets.

* independent colonies - well, some simply don't want to be inside your empire (they will change their mind once trans-dimensional alienes come), overall they are neutral and can be subverted to join the empire.

* rebel colonies - imperial colonies that decided they don't want to be part of the empire anymore, very dangerous since it decreases the stability of the empire and can make it all fall apart. You can grant them independence if you are too weak. All rebels are allied, have shared fleet and try to conquer the imperial home planet.

* plague - a plague can break out in a colony (usually if there is an exotic fauna/flora) then that plague will spread unless quarantined.

* alien eggs (from the "Alien") - there is one planet (or more) where there are alien eggs burried, you don't know where but eventually someone will make a colony there and the aliens will hatch, then they will spread similar to a plague.

I still get a problem with these independent planets... I don't know, it kind of feels wrong to me. I mean, Terrans auto colonize and sometimes (based on logical factors) that planet will join the empire and sometimes not. Is it just me or is this mechanic flawed?

This sounds like a great idea!! I would play it for sure!

- make like 40 races (a bit insane ), problayby just parametrized (like: Race A is scientific + aggressive)

I'm not sure why every race needs to start on exactly one planet, space travel is old, colonies have been built, wars have been fought and settlements have been annihilated,

so some 6-8 races spread out is believable, let them colonize different(and same) types of planets to give them unique colonizing patterns a portrait and an ability/skill

Althrough, I'm not sure what should happen if you attack a planet of that race (does other planets will help them?). Note I would prefer to not implement any sophisticated algorithms for neutrals, since that's not the scope of the game.

The other planets build more defenses/ships(since they can't arrive in time even if they wanted to help), and i think their diplomacy(willingness to join) should be partly dependent on their military strength anyway.

I still get a problem with these independent planets... I don't know, it kind of feels wrong to me. I mean, Terrans auto colonize and sometimes (based on logical factors) that planet will join the empire and sometimes not. Is it just me or is this mechanic flawed?

It's kinda boring, hence different races.

Another option is to have planets hold "friendly ties" with other planets and have their diplomacy towards the player be influenced by this.

It'd basically replace the physical universe's(as i think you described)

The galaxy is made of a few dozens of planets (not that many) connected by routes (so traditional here).

with diplomatic routes.

Make these routes overlap largely(aka planets make friends with neighbouring planets) and the player would be able to grasp these routes.

You know, I don't want this so complex. All these neutral planets with their diplomacy and their fleets and everything...

I turns into a traditional full blown huge 4X :( I want something different, smaller, more minimalistic, cozy and somewhat unique.

Like the Emperor of The Galaxy feel. You have these planets (Terrans only or humanoids aliens as well) and they belong to you or are pathetic passive neutrals. You grab these planets (if you like them) and then improve and defend them and crush rebelions. Then comes the threat from the distant parts of the universe/galaxy and you need to fight to keep your empire secure.