Certainly they have to share certain elements, and I do not deny they will modify the environment. What I argue is that it will not necessarily lead to a mass extinction, or something resembling that.
Also, to argue that genes "consider" only things during the lifespan of the organism that carries them -- this is simply not true. In much longer time periods, those organisms which are not adapted for long scale existence (those that have a habit of wiping themselves out by environmental ruination) will die out. There is just as much advantage... actually, far more advantage, in genetic predisposition to sustainability.
I did not say they did. However, any organism is capable of destroying itself when given a position similar to that of humanity.
For example, if you have deer in Yellowstone and no wolves, the deer have no natural predators, their numbers expand exponentially, and when a particularly harsh winter comes around, a great number of them starve to death. The deer is not intentionally wrecking its environment. It is an animal that has adapted to its climate very well for several millions of years; it's not inherently self-destructive. But it reproduces as long as conditions are favorable as much as it can. Similarly, a bacteria colony, allowed to grow unchecked, would out-mass planet Earth within a week. But that never happens because it's constrained by its own byproducts.
Organisms will expand when, where, and however they can. Sentient organisms doubly so, since they are fully capable of grasping what exactly is at stake. That is the number-one priority of a given lifeform: self-preservation, most chiefly of
the individual. Over time less stable life forms will collapse, but that inherent bias will always remain, and when coupled with the ability to make decisions and evaluate their outcomes, can and will result in behavior that is negative for the group but positive for the individual.
"Better you than me," is and always will be the name of the game.
Obviously, but as you'll note, life has managed to do all those things in many vastly different ways. Thus, I will suppose that a civilization can do the things necessary for its survival in a number of vastly different ways. Certainly, some base attributes will be the same, but building off of these could lead to any number of conclusions, only a few of which resemble humanity.
A possibility, but the conditions that arise to produce a sentience capable of doing much of note are fairly restricted. It could be that a creature could come about that could concentrate heavy metals and thus didn't need to mine. One may look at the dolphin, elephant, or squid for examples of extremely intelligent creatures. But ultimately the creature must be fathomable by people--at least for the purposes of a game--to be of any use.
The trouble is that from the perspective of humans, as interesting as these creatures might be, they don't use tools--more specifically, they don't make tools that make tools. You are unlikely to see a dolphin, given however vast an evolutionary time period, build and pilot a spaceship. They have societies of their own that we can observe, yes, though we can't really interact well with them... but to our perspective they are ultimately boring, because they cannot get off the rock that spawned them, they cannot manipulate their environments in a large scale, and thus other than whatever ecological niche they fill, their existence beyond the reference frame of their ecological is trivial. If they were to go unobserved by some life form in a larger frame of reference before their extinction, their loss would be trivial; they may as well have not existed. They don't represent a potential for change in a larger-reference, and thus to a creature that does (ie: a human playing them in a game) they may as well be another beast. These statements obviously depend on the frame of reference in question, and I am assuming the human's frame of reference is in fact larger. Something with a bigger reference frame than humanity could see us the same way, but that's tangential.
Unless the creature does have that potential to alter its environment, either biologically or mechanically, it will ultimately be of little consequence to play as, because ultimately, the human
does have to identify with it in a game.
Long-winded point condensed down, I believe the set of paths in which an organism might develop that is capable of doing that are much more limited than all the ways in which an organism might simply live and evolve, however successful it might be.
I did not say undetectable, merely unrecognizable. We can detect plenty of things and observe the changes that they perform on the environment around us without wholly understanding why or how they're happening.
Taking the above point, from a game standpoint, as a human will be dealing with these entities, the human must be capable of understanding them and utilizing them; otherwise they may as well not exist. From a realistic perspective, they exist, but their utility (materially or in terms of knowledge) is limited for however long they are unrecognizable or unfathomable.
