One of the most important moments in Persona 3 FES is when Ryoji gives the player the choice to either kill him or spare him on New Year's Eve. The choice to spare Ryoji, and thus fight against the undefeatable goddess Nyx, is clearly presented as the correct choice because the player's allies unanimously decide to go that route, but it is within the player's power to go against that decision and choose to kill Ryoji, which means the heroes lose their memory and live peacefully until Nyx destroys the world. It is a classic choice between the easy road that leads to a bad, "the world is destroyed" ending, and the hard road that leads to the good, "the heroes save the world" ending, but Persona 3 puts a new spin on this choice that makes it far more interesting than usual.
The typical set-up for a "bad" ending brought about by a conversation choice is that the ending is short and pretty much inconsequential. One of the first games I ever saw with such an ending was an old SNES game called EVO: Search for Eden, where you were given several such conversation choices (the choice to join forces with the Tyrannosauruses or Birds in the middle chapters), and in every case choosing the "bad" choice just gave you a short "this is how you die" sequence before kicking you back to the map screen. Another one I can recall from that era is the Breath of Fire 2 "let the gate remain sealed" ending, which mostly just leads to an ominous image of an army of demons, and little else. In both of those examples, and a few more that I can recall off of the top of my head, such as in Suikoden 2 and Suikoden 5, the "bad" ending doesn't even give you a proper roll of the credits, just a brief bit of narration and a few images. For the most part, these endings exist solely to say "you made the wrong choice", often by showing the world ending or something like that, and very little else. The "kill Ryoji" ending in Persona 3, though, is very different.
One factor that makes the Persona 3 "bad" ending so unique is that it is a full ending in of itself. The actual ending is fairly lengthy, featuring a large amount of conversation between the most important characters, and while it is nowhere near the length of the game's true ending, it is still fairly complex and is not an unreasonably-sized ending at all. Further, it features a full credit-roll, almost the exact same credit-roll seen in the true ending, including the fantastic ending song. In addition, you can save "game cycle" data with this ending just as if you had beaten the final boss and brought the game to full completion. In fact, I have seen lengthy games end with shorter and less-satisfying " true endings than this game's "bad" ending. However, these facts alone are not what makes the "kill Ryoji" ending so interesting to me.
What truly sets Persona 3's "bad" ending apart is that it does not rely on any cheap gimmicks to get its point across. It would have been easy to just show that killing Ryoji was a bad choice because it leads to the end of the world, since all the game designers had to do in that case was show Nyx destroying the world, but that would just be a predictable, boring ending that would do little but say "if you want to save the world, make the other choice". Instead, the actual "kill Ryoji" ending doesn't even bring up the end of the world of Nyx at all, but rather focuses on the themes that actually matter to the choice. After all, the heroes are not making the choice between saving the world or letting it end, they are making the choice between losing their memories so they can live peacefully until the end and keeping their memories so they can fight a battle that is supposed to be hopeless. As such, an ending that features Nyx destroying the world would go against the spirit of that choice, because it would be saying that the reason killing Ryoji is bad would be because the heroes would be running away from a battle to save the world, and implying that going the other way would lead to a victory over Nyx. However, by ignoring the entire "end of the world" angle in the "kill Ryoji" ending, the game puts the emphasis on something far more important to the themes of the game: the fact that giving up their memories for the sake of peace is too terrible a price for the heroes to pay in of itself.
As I tried to describe in my last post, the core cast of likable characters who grow tremendously and form a strong bond with each other is one of Persona 3's great successes, and the "kill Ryoji" ending works incredibly well because of that success. The ending portrays the members of SEES at a time several months after losing their memory, in which all of their growth and all of their friendships have been lost. Rather than looking up to their upperclassman as mentor figures and friends, Yukari and Junpei hardly even know Akihiko and Mitsuru and regard them distantly without any of the familiarity that would have become common by the time you make the choice. The characters have forgotten Aigis entirely, and she is doomed to just watch on from a distance, completely forlorn. Mitsuru has forgotten the way her father died and the reason for his death. Everything the characters gained from their many months of struggle and sacrifice is gone, and instead they are making hollow statements that echo the words of Takaya, the misguided and possibly insane man who is one of the game's major villains. The entire effect feels incredibly tragic, as if the hero undid everything that SEES managed to accomplish and destroyed everything the members of SEES believed in with a single act of betrayal. This ending truly works well to show exactly why the choice to kill Ryoji is a terrible one, and as such manages to surpass almost every "bad" ending I have ever seen.
One more thing I want to mention about this ending is the way it parallels the true ending of the game so well, but that will have to wait until I actually get a chance to write a bit more about the true ending. However, I will say that that because of both that parallel and the nature of the "kill Ryoji" ending as I have discussed above, this is the one of the few "bad" endings (and the only such ending that occurs before the end of the game) I have ever seen that really adds to the experience of watching the true ending. This is one of those endings that should really be watched by anyone who plays the game.