“Final Fantasy 7 Rebirth” is one of the more ambitious RPGs of the past few years. It mostly covers the second act of 1997’s “Final Fantasy 7,” where Cloud, Tifa, Barret, and Aerith chase Sephiroth, a former war hero turned vicious murderer, across continents oceans in a bid to stop him from destroying the planet. This portion of the original “FF7,” released in 1997, is messy and unfocused, with what amounts to a MacGuffin hunt as its foundation, and it only establishes an identity in its latter half, before the game switches to a different focus at the end anyway. That’s not an easy or even appealing concept to build an entire, lengthy new remake around, but Square Enix answered the challenge with an elegant narrative whose earnestness helps cover some of the game’s clumsier design aspects.