If Squall isn’t dead, then why doesn’t he have a face at the end of the game? Why is it so scary?
I think the answer’s fairly simple: it’s representational. It represents his past self fading away, and that he never truly experienced life. TVTropes says: “It may represent emotional emptiness, loss of identity, or guilt feelings, given the preceding scene where he participates in passing Ultimecia’s power on to Edea.”
He’s “introverted, cold and taciturn”. Without any connection to the world, he may as well be nothing to anyone. He’s not even another face in the crowd. He’s not even a memory. He made it hard for people to get to know him, or even remember him.
Squall had these thoughts when he considered Seifer’s fate:
Seifer… You’ve become just a memory. Will they… Will they talk about me this way if I die, too? Squall was this and that. Using past tense, saying whatever they want? So this is what death is all about… …Not for me. I won’t have it!!!
I won’t have it!
I’m not having anyone talk about me in the past tense!
Ultimecia has the same scary facelessness. She isn’t always without a face though:
Ultimecia’s fought a total of six times, twice within Edea, once within Adel, twice in her own body, and once when junctioned onto Griever. There are four final boss battles, the first phase being against the normal Ultimecia.
We’re fighting forms of her, but never really the real her. We’re fighting against empty shells with her personality. We never really get to see the real Ultimecia until the end. By then she loses herself to her ambitions. Ultimecia took control of others to manipulate time, but what about who she was? Edea and Rinoa were able to regain of their sense of self, but not Ultimecia.
TVTropes says: “Ultimecia’s final form is similarly faceless, or rather its top half is, with the recognizable human Ultimecia forming the bottom half. The top half drains the bottom half in order to sustain itself, so the facelessness may represent being divided against oneself in a way that causes emotional emptiness, loss of identity, or guilt feelings.”
Even though the bottom half looks like a pendulum, the whole of Ultimecia also resembles an hourglass. But as Ultimecia draws all of existence into her, the top half is draining the bottom. The “sands of time” drain Ultimecia. She’s slowly fading away, only backward to represent the manipulation of time.
“So far, the best analysis I have this for this screenshot is that Squall feels empty, that he losing his sense of self and everything that comes with it. He’s having trouble visualizing his memories, or even remembering reality from fiction. Think back to what Ultimecia said, at the end of the last battle. “Reflect on your… Childhood… Your sensation… Your words… Your emotions… Time… It will not wait… No matter… …how hard you hold on. It escapes you…” His life is fading from him. You can’t hold on forever.“