My suggestions :D (mostly life-on-planets related)

[Kacperozaur]

Here's some suggestions from me :
Stars
- There should be classifications of stars in the game ! (M to O and such)
- You should be able to make any class of star! Anything from red and orange dwarves to supergiants hypergiants!
- Also different sized stars should have different life spans (not sure if that's true and if it is if it's realistic but I'm still gonna post this >_>)

Life on planets
- if there is a higher than for example 0.75 life likelihood on a planet (may vary), there should be a green or green-like color popping up on the surface, and with time, slowly dominate the surface.
- If there's a really high chance of life on a planet (for example 95%) There should be some sort of proto-civilization if you wait long enough (anything from 10,000 to maybe 1,000,000 years) and in the bar on the right there should be an image that a proto-civilization exists, something like the message you get when you discover a proto-civilization in stellaris.
- I mentioned a text or image saying that a proto-civilization exists, Well you should make it for life! For example,if there were no life it would say "life: none" and if there's simple single cellular life it would say "life: single cellular" and show a picture of bacteria, and so with for example a stone age proto-civilization, and show a picture of some aliens bashing on rocks xD And if a civilization reached space age you could see satellites orbiting it (amount of satellites would increase over time) and maybe you could observe the civilization send rockets to their moon (if the planet has a moon) and also maybe to other planets that are habitable enough. And also the life should develop over time, from single cellular, to multi cellular bacteria and such, to a civilization!

I think that's all I wanted to mention, besides also being able to make galaxies, and rings and asteroid belts easier. If you have any more suggestions people, leave them in the comments! or just be a douche there >_>

[Angel Armageddon]

I don't intend to bash your great suggestions, but I believe that this is a super realistic gravity simulator. Not God simulator. But I do agree about hoe the land should turn green after some time. But a civilization making stuff and sending it into space would take to much cpu and graphics card power to run, and is unnecessary. But if it was more like Space Engine, where is says (Life: Simple cellular, etc.) But no lights and aliens sending stuff into space? Sure, go for it. But this is just a bit overboard.

[Pizzaeater1K]

- Also different sized stars should have different life spans

Thats already in the game.

[MD2903]

Currently this simulator only simulates evolution of main-sequence stars, heavier stars will immediately explode. You can make hypergiants in this game, but only if you put "realistic" off.
I'd like to see the spectral class of a star when you make one. Example: I make a Star with a luminosity of 1.400.000 suns and a temperature of 23000 K, The spectral class would say: B0Ia+

In a blog they stated that stellar evolution will be completed for more star types, in alpha 21.

L, T and Y type brown dwarfs would be very realistic too.

I like the idea of a habitable planet turning green, and saying what kind of life there is, like unicellular life.
But (proto-)civilizations is too much, this is meant to be a realistic spacesimulator.

[Kacperozaur]

So, I've come to a conclusion, some suggestions were good, some where crazy, but we learn from mistakes don't we? xD

[Niel amstronge xd]

With this part about life..  I agree all .. That should be in the game! US2 is universe simulator so there should be life in it!