I am pro live asteroid i.e. Gigashadow (Lexx) or Great A'Tuin (Discworld). also I like the idea of animals/critters to make the world seam more alive (it gives you more to kill), as i have said in other threads
It also gives the devs quite a bit more modeling and scripting work which could otherwise be spend on making the game less buggy.
Carnivorous plant - rare, remarkable method of reproduction: the seed plants on the surface of planets (usually with a high iron content in the soil), if it set to metal mine, instantly grows and explosion scatters seeds side. If your unit comes into contact with the seed, it germinates in and instantly release more seeds. If a unit is moving in a group, issued the first plant the seeds may well cause a chain reaction of destruction units.
I was thinking passive animals that where as much background. But like elexis said rather the time/money went some where more important, this is a very limited budget for a game and this should not be high priority.
Idea: Atmospheric Vapour. This strange form of life consists of simple molecules that float innately in the air, composition made up primarily of Nitrogen, Oxygen, Carbon Dioxide, and traces of other gases. The Vapour is known to cause corrosion on mild steel, and exposed aluminium. Fortunately modern alloys and ceramic armour is highly resistant to rust, so this species of animal presents no hazard to your plans for planet smashing. Good idea for an animal, yes?
Not really necessary for the game as is, but would be good if it was possible to code in netural/hostile npc stuff for mods.
You should encounter nests of baby animals randomly on planets. If your units tread on them or they are destroyed by gunfire, you lose the game for being a horrible person. INTERESTING TACTICAL DEPTH.
I like this as a general idea, having startled wildebeest stampeding away from you for example, but I wouldn't like having animals that can pose any real danger as it would mean people losing games on pure luck. But more importantly, Uber said during the live cast that they would not be including animals.
How about Warcraft sheep? Generally I like the idea of random things, which could casually blow up on the battlefield. They even don't need to be torn apart, but just fly around a little and be gone. I guess real monsters as a third neutral party won't fit, are too much effort and a balance problem.
That's a shame, I'd have liked this kind of thing, bird like animals scattering out of the trees as your army rolls through or like you say herd animals making way for the war machine. I can understand that decision however. The inclusion of something that presents no addition to core gameplay is something they probably wouldnt have time to do. Maybe something like that might crop up later if the game is developed past release. If the game is developed post release wouldnt it be cool to have community involvement in on prioritising future content : D kinda like how it was done with the stretch goals in the kickstarter.