menu screen

[Treewyrm]

Erm. Not exactly. Menu uses same in-game cutscene engine which is used for all real-time cutscenes in game, including landing on planets, equipment rooms on bases, etc. They can be modified to a certain degree as a scene, but not really too much, for example we can't make new models for characters but we scan reskin them. That being said menu screens can be done, they aren't too hard, however base rooms are a bit tricky.

Animated suns aren't exactly suns, those are merely effects placed. Suns in game are complex objects made of various elements, such as actual circle, glow, lens, spikes, etc., they use scaling and fading techniques for various things, like "blurring" effect when passing through nebulae, etc. Particle effects don't have those features and would cause graphical problems in certain situations. More importantly effects don't maintain glowing size regardless of range between you and sun, i.e. there wouldn't be light corona.

Transports and other "moveable" objects don't use engines at all, basically the script tells to move object from point A to point B, and nothing else. They don't move by themselves, hence you don't see proper engine effects.

Rocky planet with animated surface can be done, it's merely effect which can be attached to special invisible object put on top of the planet object.

Bloom effect from stations is also used on nomad lanes to feature in 4.85.