I feel like a horrible, horrible person. This reminds me of last year's "Changes", in that the protagonist's every move seems to result in horrible consequences. Considering that the failure message seems inevitably to be "you are happy enough", it really does seem that the ideal ending is to fail in one's stated purpose.
The other thing it reminds me of is a short story I read once, by Ursula K. LeGuin. Both involve ships with similar crews, the introduction of an alien being to the ship, and the reaction to it. Google tells me that the story is titled "Intracom". I have also since learned that the similarities are entirely coincidental -- "Coloratura" certainly deals with the situation in a more realistic fashion, where "Intracom" tended towards the comedic.
Spoilers ahoy.
What really makes it work is the alien perspective. That perspective is thorough and immersive. We move and act as this alien being, and we identify with its goals; yet, because we are dealing with humans, we know as the protagonist does not that things are often not quite what it thinks. Every step that we take is reasonable, from the information we have as the alien protagonist. But ... step out for a moment, and consider the events from the point of view of the crewmembers, and suddenly it's not so sensible anymore. It actually took me an uncomfortably long time to understand why the crew reacted to the "newsong" as they did. As another reviewer points out, this particular event involves a month's worth of steaks turning into a meat golem and jumping into the sea; and yet, even now, knowing this, I am a little taken aback by the shock and horror that resulted. That is how immersive this is.
Later in the game, we manage to connect with one of the crewmembers, enough that we gain a little more understanding of the world around us. The descriptions of the world change to reflect this: things are no longer described in alien terms, but with human names. That is thorough mimesis.
The ability to colour other people's emotions is a neat trick, and it is nice to see how the story plays out with a tweak of the emotions here and there. The sequence of events requires that the story go a certain way, so immediate effects are divided between "change in text" and "choose now to continue the story". The "change in text" bits are actually often sufficient: a lot of the opportunities to tweak emotions occur when two or three crewmembers are in conversation, so it is interesting to see the resulting interplay that occurs when the tweak is applied to one or another crewmember, and towards one or another emotion. Still ... I wonder if the outcome could have been affected by some change in attitude early in the game....
It may be worth pointing out that this amounts to emotional manipulation. No, it doesn't just "amount to", it actually is, in a purer form than any human being could manage. Our protagonist does everything through manipulation, and it's actually quite creepy when you think about it; but in the immediate present, it seems perfectly natural. Where do we draw the line between communication and manipulation, anyway? And our protagonist finds its way back to home essentially by using the dead weight of one of the crewmembers as ballast. From an outside perspective, one could easily describe our protagonist as evil incarnate, and yet, knowing what it's thinking, we know that it certainly isn't malicious or purposefully destructive.
And even as calamity piles on top of calamity, it seems as though, well, just a little more interference couldn't hurt ... right? And, y'know, sometimes we're actually trying to help these people.... Baby steps. The disasters of the world are built on baby steps. And I think that one thing we can learn from the whole story is that a lot of the evil that happens in this world is not born of malice at all. And sometimes ... is it "evil" or do we simply not understand? Look how happy and blissful those comatose crewmembers are ... how blessed.
On the whole, I enjoyed this very much. It's like a very fluffy, juicy Spanish omelette, served with Melba toast and maple-glazed Canadian bacon. Fair-trade coffee, with fresh cream, no sugar. Lots of broken eggs went into this, but it makes no apologies (why should it?) and it's totally worth it.