This.
Gun Mute
So, the hardest problem that endings in videogames have to face is that an ending (like more or less every part of the game) really needs to reward the player. But the best possible reward in a game is the ability to do more stuff, and obviously you can’t do more stuff after the game ends.
[spoiler]Gun Mute’s protagonist has two big character hooks: he can’t talk, and all his social interactions are carried out through the limited agency of nodding and shaking his head; and, of course, he is great at shooting things and operates in a world where most problems can be solved by shooting things.
Now, personally I found the big end-boss guy the least interesting opponent of the game, but that’s not the real problem: after the climax, there’s an epilogue, where you discover how the surviving NPCs are getting along and what’s happening to the town. On the one hand, I’m usually a sucker for this kind of The World According To Garp strung-out epilogue; but on the other, rather than being this upbeat sequence that reminds you of what you were fighting for, it felt to me like a diminished, sad remnant of a thing. Partly because you’re mostly good at shooting things, and there’s no shooting in the epilogue. Partly because the boyfriend is a bit too generic to be a really compelling love interest. Partly because, without shooting everything, the limits of Mute’s muteness become a lot more acutely visible. To me it felt like a hollow victory. I’m not sure whether this makes it a failed ending - pathos is a fine note to go out on -, but I’m not sure it was the effect desired.[/spoiler]
Violet
[spoiler]Right at the end, it turns out that Violet was actually watching everything you did: she had set up a secret camera to watch you. Also, she fake-out pretends to leave you as a joke. Both of these are totally not-cool things to do to one’s partner, and twist a previously quirky-and-conflicted-but-ultimately-sweet relationship into something dysfunctional and co-dependent and controlling.
This effect wasn’t intended by the author at all: the camera was put in to resolve some problems with the plot-logic (imaginary-Violet was hurt by the destroying of her gifts, but understood the context; it’s hard to see how real-Violet would.) More importantly, it’s sort of inconsistent with the general tone of the rest of the game. Moral of the story: test your endings with readers, and solicit feedback on things like tone and meaning and so on. Otherwise, you’re vulnerable to an interpretation that’s a) totally obvious to everyone except you, and b) turns your story into something you really didn’t want.[/spoiler]
Anchorhead
[spoiler]Anchorhead is so damn good at the ominous buildup that there’s no way that any actual conclusion could live up to it. Uncovering the dark plans and evil machinations is great; it’s still pretty great when the mask has been drawn back and everything’s going to hell; but once you know how everything fits together and what you need to do in order to win, it kind of kills the atmosphere. The last puzzle is absolutely the least interesting.
And it’s got the problem of most Lovecraftian stories that, despite being Lovecraftian, want a heroic conclusion: you set up the Enemy as an ineffable monstrosity more unimaginably powerful and alien than a mere god could ever be, symbolising the total, monstrous indifference of the universe and the inability of small, insignificant humanity to have any meaningful impact on it, making a mockery of human rationality, faith and capabilities. Then you have a plucky hero defeat it with a shotgun. (Or, in IF, by the logical manipulation of machine components.) You can have one or the other in your story, but they can’t really co-exist without one or both feeling contrived.
These are pretty fundamental problems, to do with the sort of story Gentry was trying to tell, rather than any specific failing on his part.
I dunno about the moral here. There’s “your players do not have the right to a happy ending, even if they really want one,” that’s pretty important, although how much it applies here I’m not sure about. “Getting the ending absolutely right is sometimes not just difficult, but impossible” is probably closer to it.[/spoiler]