It's been mentioned a few times, but Resonance of Fate is probably the most obscure one I own. While they definitely had their moment in the sun when they released, I will have to admit that Valkyria Chronicles and Eternal Sonata seem to have been forgotten by time.
The former definitely gained a pretty good following until Sega shrunk its fanbase by putting the next two titles on the PSP rather than continuing to put them on the PS3, as well as not localizing the third one. So while its combat system at the time is definitely unique, combining elements of a top-down SRPG with 3rd-person shooting, it hasn't seemed to have left that much of a mark after a year or two of the first game's release.
The latter was released on 360 then ported to the PS3, but not before being given a rather significant overhaul, and I'm not simply talking about adding two characters. They fundamentally altered the way the story was presented, as well as outright deleting, adding, and editing certain cutscenes and critical dialogue in order to make the story more coherent and cohesive. However, it was pretty heavy-handed, and while it was cool to talk about the ending of the game and everything it entailed, it too faded away rather quickly.
