Just knowing about the Shin Megami Tensei games used to be worth some serious hardcore points. In a genre that's largely populated by pallid Tolkien ripoffs and bizarre fantasy/scifi cliches, the SMT series tends to go after themes like the benevolence or malvolence of an omnipotent God, the existence of free will, and the ongoing destruction of the world around us.
The Digital Devil Saga games are one of the offshoots from the main series, much like the obscure Persona titles on the PSOne (and would someone get around to translating Innocent Sin already?). If you played the first game, you played one of the best and most memorable RPGs of the last year; it took Shin Megami Tensei: Nocturne's engine, combat, and predilection for truly massive dungeons, and welded a lot of drama, humor, and personality onto it.
Digital Devil Saga 2 is its immediate and direct sequel, which... presents a few problems. If you haven't played the first game, then you're not going to have much in the way of a clue as to what's going on; the original Digital Devil Saga was mostly spent establishing these characters and setting up their world, so you could crack into the epic-level antics of this game.
This is doubly complicated by the fact that these are RPGs from Atlus, which as a publisher, is the best thing to ever happen to eBay. These days, finding the original Digital Devil Saga, after everyone found out how good it is, is a little difficult. If you've missed the boat on this series up 'til now, you've got a problem.
The original game was about a place called the Junkyard, and a tribe of warriors called the Embryon who fought for survival within it. Under mysterious circumstances, the Embryon found themselves branded with bizarre symbols, which allowed them the ability to transform into demon forms: their Atma, which are only controllable if fed with the flesh of living creatures. To survive in the Junkyard, the Embryon were forced to constantly fight and devour their opponents.
At the end of the game, the Embryon thought they'd found the way to the Junkyard's promised land: Nirvana. Instead, three members of the Embryon--Serph, Gale, and Argila--find themselves on Earth in the mid-twenty-first century. What few humans survive live deep underground, to hide from the black sun that burns in the sky, the light from which turns people to stone. Even in the Underground, the few surviving humans struggle for survival against the half-demon monsters of the Karma Society, who constantly abduct humans and use them for food.
Going any further into DDS2's plot would spoil the hell out of the original game, which I don't particularly want to do. RPG fans tend to be a little clannish, especially these days, and I don't see the need to ruin the DDS story for all the people who haven't played it yet.
Suffice it to say that the game has a somewhat surreal plot, dealing with heavier themes than most Japanese RPGs, such as man's relationship with God and the nature of reality. That plot backs up a solid game with an equally solid combat engine and character growth system, which I'd stack up against any other game out there.
In a fight, each of your characters will usually transform into his or her Atma, which allows them access to their spells and special moves. (If they're prevented from shapeshifting, or forcibly reverted to human form via one of a variety of abilities, they'll be forced to defend themselves with guns.) In Atma form, you can use the trademark spells of the Shin Megami Tensei series, complete with names that only sort of make sense. (Remember Wizardry, and how you had to memorize all the nonsense phrases that corresponded to each spell? The same thing's going on here.)
You'll want to have access to as many elemental attack spells as possible, since DDS2, like the first game and Nocturne, uses the Press Turn attack system. If either side scores a critical hit, uses an attack that exploits an opponent's weak spot, or is hit by an attack they're strong against, that side'll earn another Turn icon. It's theoretically possible to prolong your turn indefinitely as long as you can keep hammering away at your opponent's weak points.
Conversely, of course, they can do the same thing to you, but the Press Turn system rarely allows either you or your enemies to run the tables the way you can with, say, Magna Carta. Unless you are vastly overmatched by your enemies, which rarely happens, Press Turns allow momentary advantages and not instant losses.
All in all, this is another great RPG on the PlayStation 2. The only thing keeping me from giving Digital Devil Saga 2 an unqualified recommendation is how hard it is to find its predecessor. If you've already got it and beaten it, you'll find DDS2 to be a long and satisfying RPG experience. Once you give it a try, you'll find yourself hooked.