Radiant Historia begins well, with its protagonist Stocke being assigned to escort an agent possessing vital information out of a war zone. His efforts go awry, and instead of dying at the hands of a Super Powerful Enemy, Stocke is taken to a crossroads outside of time, where he is instructed in the use of time travel to alter history. Stocke doesn't have free reign over when to go, instead he faces a choice very early in the game that diverges into two distinct paths history can take. Various junctures along these two paths are the periods to which time travel is possible, and while I can't claim to have been blindsided by most of the plot developments in either path thus far, neither is anything repellent.
Many aspects of Radiant Historia remind me of the Choose Your Own Adventure books, actually. An early incident at a plugged mineshaft is a good example, as the proper path requires Stocke to acquire an ability from the other timeline, or else he'll waste so much time waiting for the enemy to come out of the mine that all will be lost elsewhere. The need to go through certain story bits is made a lot less bothersome because pressing Start will skip cutscenes, but it's still noteworthy. Also just like the Choose Your Own Adventure books, some of the decisions to be made (like the blocked mineshaft) will result in a sudden ending that requires going back to an earlier juncture.
"Many aspects of Radiant Historia remind me of the Choose Your Own Adventure books..."
Enough of the time travel stuff - what is combat like? To start, battles aren't random: Stocke can smack enemies with his sword to either get them out of the way or to incapacitate them for the first turn of the fight. Once it begins, combat evinces a rather novel use of the turn-based system. Having the enemies in several rows that alter their damage dealt and received is nothing new, but being able to smack them between the rows by use of special attacks is. Enemies can also be forced onto the same square in order to hurt more than one opponent concurrently, but once any enemy has a turn, they will automatically disentangle. This gives an actual reason to use the seemingly pointless ability to swap turns with the enemy, since more damage (and better rewards) is the result if the player's team can string a combo together. Early in the game just pressing Attack remains a viable (if boring) option, but later the enemies get strong enough that beating them down as quickly as possible is advised, or at the very least healing in battle is likely to be necessary. Enemies also sometimes anoint specific squares with statistic-enhancing abilities, and when the attack boost these squares make possible is enormous, knocking the enemy out of its special spot is very wise.
One aspect of the game that makes no sense is how character levels stay the same regardless of the time to which Stocke has just zipped. Having Stocke remain the same level makes logical sense, but no one else travels through time, so having their experiences from the future carry into the past is a little odd. I understand why the development team did it, though: Stocke will be hard-pressed to complete the game by himself, and it helps enormously to have teammates who can carry their own weight.
I could gripe that the need to smack enemies back and forth drains MP, but the game is generous with dropping MP-restoring items, and save points can fully restore characters (though the items that do this are fairly expensive, so no unlimited restoration capability). Both stories are full of standard RPG plot elements, so don't expect to be genuinely surprised once they get moving. I deem these relatively minor problems when fighting is engaging and the stories aren't boring, however.
Without going into spoilers, there isn't much else I can say. Yoko Shimomura's score isn't her best work, but it's very good nonetheless. Sidequests aplenty become available by talking to NPCs throughout each town, giving a good reason to interrogate people regularly, since their topics of conversation change as the plot progresses. Atlus has done a typically good job of localization, though I haven't seen much humor, so don't play it for a joke parade. It's fun to play, the stories stay involving, the audio and video are nice accompaniment, and I pronounce Radiant Historia a DS game that is very likely worthy of ownership. Whoa.