EDIT:

Never mind, sorry. I've managed to get all three endings now and the third one was the most satisfying in terms of presentation, while the first and most easy one felt a bit incomplete - not because of what was happening in the cutscene, but due to what happened afterwards.

*SPOILERS'

1. Ending: You watch the cutscene, and when it's over, you're somewhere else inside the cave (why?), you can move freely but your map is not available anymore, there is nothing more to do but find the exit, which will teleport you right outside the cave. You go back to the base camp, hug Amani, without you or her or ART commenting on what happened (despite their chatty disposition during the rest of the game), and suddenly the credits roll. The way it was presented was very anti-climactic and a bit confusing. If the game had ended right after the cutscene, it wouldn't have been worse (probably even better).

2. Ending: You watch the cutscene, and when it's over, you're outside of the cave, you go back to base camp, hug Amani, credits roll. Same as above, but less confusing since it's more clear that the game is over and there's nothing left to do. Also, what happened in the cutscene needs less talking about, and since Liang made a lucky escape, the hug is better motivated.

3. Ending: You watch the cutscene, and when it's over, you're still at the same place, you have to solve one last 'puzzle', the game ends with Liang speaking his last lines, then the credits roll. It's not necessarily my favorite outcome of the story (although I like it, too), but it's the less confusing and most satisfying ending in terms of the story-telling; it gives you a certain conclusion and doesn't feel as rushed as the other two.

(Just to explain why I even started this thread; because after the first ending I was worried that I had missed something and that the game had ended prematurely.)

Three endings? Really? I only discovered two! One raised an alien version of a bio-dome, one caused a spaceship to be launched. What have I missed?!

When the spaceship launches, you can either get the hell out of there, like Amani suggests, or ignore her and stay. The third ending I referred to is Liang staying inside the spaceship.

Huh! I have to try that next play-through, then.

You could also just load your last autosave that the game creates shortly before the final cutscenes are triggered, but it sounds like you're eager to play through the whole game again and the new ending would be an additional motivation? ;)

Actually, I've already started another play-through. :-D I'm going at a more leisurely pace this time, trying to see just how high I can raise the total biomass, what the most efficient solution to each puzzle is... A third ending that I haven't seen yet? That just makes for a convenient excuse when my husband asks why I'm still playing a game I've already finished.

I might have been tempted to just load the last autosave to see the last ending - that is how I got to the second ending - but I think it was already overwritten by the very beginning of a new game. So onward into the cave we go...

Another interesting, but probably a lot less enjoyable approach would be to see if it's possible to completely ruin the ecosystem. :/

To me it seemed like there's a certain possibility of a species to go extinct if you don't treat the environment responsively or even purposefully exploit and destroy it. That's something I found equally scary and fascinating, because while it's not a very attractive design choice in terms of gameplay, it certainly gets the message across about how delicate the balance of an ecosystem can be.

Then again, whenever I thought I was stuck due to lacking resources, those busy jellyfish bees came to my rescue, and you don't need to solve all puzzles in order to complete the game, so maybe they made sure you can't lose.

I'm pretty sure its possible to destroy the ecosystem where you cannot win, but it would entail a lot of directed effort. Destroying all the "beehives" would certainly be part of it.

I think it should be possible to lose all phyta 'crabs' to predators and magma, all larians to feran zoa seeds, then destroy all cephads and waste the last cephad spores on turning already inhabited terrain from acidic to alkaline and vice versa, but unless I'm mistaken you can't fully destroy the beehives. Even if all the jellyfish bees are gone, you can always create new ones yourself, as long as you manage to get the biomass to level 2 and have a few halid or hydron seeds to spare, which are easy to come by. That's why I think these cycot 'bees' in combination with the halid and hydron zoa might be enough to prevent you from fully ruining the ecosystem and losing the game.

I got the same feeling... it would be great if you could describe what you did to get those different endings.
Even though I wonder about more than just what you described (see my own thread).

SPOILER ALERT!!!!!

Ending 1: Mars becomes habitable, the harsh martian soil is now transformed. You meet and hug your shipmate, blah, blah, blah. In the room at the end, you activate the machine on the right-hand side. (This takes much less power than activating the machine on the left).

Ending 2: The spaceship starts to rise! Your shipmate warns you to run for it. You meet and hug your shipmate, blah, blah, blah. You activate the left machine, and when you get the warning you run quickly out of the ship.

Ending 3: The spaceship starts to rise! Your shipmate warns you to run for it. You decide to stay where you are. One final test before you travel who-knows-where. You activate the left machine, and when you get the warning you ignore it and stay on the ship.

1. I believe you alread found that one on your own. It requires a certain amount of biomass and stepping on the right platform below the big pods.

2. Requires a higher amount of biomass and stepping onto the left platform below the pods (in all areas where I was told to raise the biomass, I raised it to level 5, in order to get this ending; biomass was above 60, but I don't know if that's required or if it will trigger with less biomass, too - the game will tell you whether you have enough already, when you step on the left platform).

3. Same as 2., but ignore what Amani says and stay where you are.

Btw, you don't need to ALT-TAB out of the game; after the credits (you can skip them with Esc), you get the options to load your last save game or create a new one. If you load your savegame, you're at the spot where you were before triggering the ending (meaning the ending won't override your last in-game save).

I don't think you can get endings 2 or 3 without talking to the sentients and doing their bidding. If I recall correctly, part of the process of dealing with the sentients will double your power. Without the doubling, I don't believe you can operate the left platform.

Huh, that's interesting about the LEFT machine. I always wondered what it did. Guess I don't have enough biomass. Although probably more likely core power? I only have one cave that isn't maxed out, which makes for a total of 34 core power.

But what is that about talking to the sentients and doubling power? I still wonder what that "talking" is supposed to look like and how to initiate it. Is it supposed to take place automatically right after finding the correct image with the visualizer?

Talking to the Sentients IS a matter of finding the correct image with the visualizer. Those signals are how they talk, at least to Liang. You need to find the image, which is usually easy but was really frustrating once, and then figure out what they want. To get to the more advanced endings, you will have to do this repeatedly. The worst part is that there is no way to exit the visualizer screen without finding the image, which can be a bit of a problem if you've been jiggling the cursor for what feels like ten minutes and just want a break. Once you've found the image, it's usually pretty easy to get what the Sentient wants; Amani and ART help with this the first couple times and from then on it's obvious.