First of all, I have no idea why there was "Final Fantasy V" footage before the trailer. But I will admit, I am about 100 times more nostalgic for that old game than I've ever been before. Here I thought FFV was just a forgettable nothing title, but when you hear that old battle theme rocking, you just want to get Bartz back on Boco and start beating up dungeons with as a Mystic Knight.
Anyway, "Explorers". I looks like fun. Basically the combat looks like a multiplayer version of "Final Fantasy Type-0", only with a fixed slightly overhead view, solving that game's crippling camera errors. It is also much more cartoony and kid-friendly, so instead of building mountains of bodies, you're just fighting big silly monsters with your friends. And that is something I'm looking forward to doing when this game comes out. Nobody is sure when that will be, but since it at least has a window of next year, it will probably be a few decades before "Final Fantasy XV".