I`ve been working hard at it, upgrading to the best drives possible ( I think), going deeper and deeper into the galaxy, even using Black holes, which apparently don`t kill you in this universe.

I must admit the Trailer that some people insisted on putting up here, that I never saw before getting the game got me going on a quest to try and find something like the huge (or pretty big) brontosaurus type thing we see in that.

I`ve seen the huge vistas teeming with alien grass- check.

I`ve seen numerous animals running and flying about about. Even seen shoals of water fish - check.

I`ve seen more than just four ships in space. 8 so far- check.

I`ve seen tiny animals to about 4 meter tall animals, maybe 5 metres -check.

But can I find any really, really big creatures? Heck no. I`ve even entered a couple of Green systems, still very little.

I am certain they are there, as I am seeing gradually larger animals, but I guess the randomness and the procedeural generation aspect makes the die roll for it rare.

I`ll find `em... eventually.

I get the feeling that things do become more "weird" as you get closer to the centre of the galaxy.

After doing a ton of exploring, close to the starting point, I have just done a jumping session and got about 50.000 light years closer to the center. I am seeing much larger (and weirder) creatures. Still nothing super big (I'd say about 3 times my size is the max so far) but I also just got there and I didn't do that much planet exploring on the way, so let's see.

I could be mistaken, not sure if anything is known about planets being different, depending on their distance from the centre.

Also, why green star systems and not blue ones?

If there had been any logic involved during the creation of NMS then it could be that

- large creatures need lots of food, plant eaters must be feeding almost during the whole day
- plants, and lots of them, need nutrition, water first and foremost.

So to find some giants it might be good to find a planet with enough water.
And, if the core is something like a sun, the outer planets will be the colder ones, normally.
But, this all might be not true for NMS ...

The thing that colder planets are far away from the sun, while warmer ones are closer (or any kind of simulation) is definitely not the case.

Also, I wouldn't look for this kind of logic when it comes to creatures. From what I've seen, it's all just completely random. There are for example planets with barely an flora but abundant fauna. How does that work?

It would be cool if the procedural content would be created on a lot simulation data and logical conditions but this seems not to be the case (at least at the moment).

I read somewhere that the green systems had a better chance at giving big creatures, but it may have been just a rumour. I`ve been ignoring blue ones, maybe I`ll try them.

Have you noticed the lettering system? They always seemed to `F` so i`m trying to get to systems prefaced towards `A`- maybe that`ll make a difference.

The letters are difing the star's spectral class. see here:

http://nomanssky.gamepedia.com/Spectral_class

From hat I read, blue stars are the ones that have the most lush planets in terms of flora/fauna (and from my testing so far, this also seems to pan out). You need a warp drive upgrade Theta to get to them. The green ones are supposed to be one tier lower than the blue ones (and you can get to them with a warp drive upgrade Tau).
I am not sure about big creatures though, but I'd guess you'll have the best chance in the blue star systems.

Look out for highly radioactive environment: found some creatures that had been 6 m tall. Harmless ones.