By one Endless. That's the thing. More of the Endless should have been aware of our plan and should have been telling us to go for it.
And what about Cahciua and Krile's parents? They're every bit as sentient as any main character.3.) The Endless are essentially ghosts with questionable sentience, let alone sapience.
As mentioned above, with ashkin, the Endless are ONLY memory. No body, non soul. Basically, digital ghosts. When you shut down the terminals, you're flat out told that some will remain behind if they have "unfinished business". And while some of those that remain do seem to realize other people have disappeared, they seem unaware that the world around them has changed to a shade of grey.
The background NPCs are less developed because they're background NPCs.
Our actions are defined in game as a tragedy because the pretty landscape is going away and because the memories of the Endless are being erased, but it's okay because we'll remember them, which is exactly the same thing as digital recreations of them walking around and being aware of their surroundings.4.) Our actions are defined, in game, as a tragedy, but really the ONLY choice.
We're not doing what we're doing out of malice. We're doing what we're doing because it's the only thing we can do, in order to shave our world and other worlds, because the Endless are unsustainable. If we didn't do something, everyone in the Source would die, as a sacrifice to keep around the memory of the dead. And eventually, it would spread into other sources... And eventually, in time, still fail, since their isn't enough energy in the universe to keep the machine running indefinitely. So in time, a countless number of lives will be lost and everything still ends the same.
I agree it was a tragedy and it was unsustainable, but the devs wrote a story where our only option was to mass-delete a society of people who appear to be completely self-aware. That's messed up.