(I originally posted this as an entry into the Shin Megami Tensei: Devil Summoner: Soul Hackers contest, but it took so long to write that I wasn't eligible by the time I entered it. So, I decided not to let it go to waste and post it as a community blog.)
Shin Megami Tensei: Nocturne was a landmark achievement for role playing games, placing players in a situation that was simultaneously horrifying, uncomfortable, and deeply empowering. As you stand next to your teacher, who had been your guide and friend in your previous life, you watch it all disintegrate in an apocalyptic event that leaves only Tokyo standing. You are made to watch as the world becomes vastly smaller and vastly stranger; your life is irreversibly changed, and you are totally stunned as to what to do next...when a strange child drops a worm in your mouth, and you are changed forever as well.
Set on a journey to discover your place in this vast dystopia, you will discover that you tread a land that embodies the very cycle of life and death, and that you will be the deciding factor in what the new world becomes...or if it is even reborn at all.
Aside from the epic setup, eerie world, amazing plot twists, and grand conflict, Shin Megami Tensei: Nocturne had great pacing, blistering difficulty, and a customization system that is rarely, if ever, rivaled. Imagine, if you will, a cross between Final Fantasy V's job system and SMT's usual deep demon system (given a boost this time around thanks to the Amala Labyrinth and the four tempers which you can resurrect and re-fuse to boost stats). It combines everything great about taking power from the world around you (the demon system) and developing one's own inner strength (the magatama).
The pacing is also simply incredible. At first, you will feel highly restricted, and the game will be relentless in attacking you. But develop some strategy and make it to level 30, and the demon system begins to really, really, really open up. From here on in, there is always another power to pursue, another demon to fuse, and another quest to finish. In a twist of genius, when one has hit the final level (99) you can begin to make 2nd generation demons, resetting their levels and building them back up again so they can have skills like the omnipotent Pierce, which entirely ignores enemy defenses. The magatama also make for difficult, irreversible changes to your character, causing you to tread lightly and weigh the pros and cons of each decision you make about the development of the Demi-Fiend.
I've spoken of it briefly before, but there's just nothing QUITE like the world of Shin Megami Tensei: Nocturne. Digital Devil Saga and Ico have a similar sort of aesthetic, but the characters, in their muted expressions amidst a dying world that has suffered a fatal blow, really drives the point home about the tragedy that has occured. The visual designs of each of your friends after they (SPOILER STARTS HERE) transform into avatars for various demons and ideals (Spoiler end) is amazing visual shorthand for showing how people change and twist to become champions of the world that they fight to realize. The art style, by the marvelously talented Kazuma Kaneko, is one of the series' best, showcasing stylized versions of religious icons from religions all around the world, including Judeo-Christian, Hindu, Greek, Roman, and Japanese mythological pantheons.
All in all, Shin Megami Tensei: Nocturne isn't just one of the best in the SMT series, or just one of the crown jewels in the PS2 library. It's one of the best games of all time, and an exemplar for video games as some of the greatest art mankind has ever conceived.