The resurrected version of Dungeon Fighter Online is being run by developer Neople, not Nexon. The studio plans to begin the alpha test of DFO tomorrow, May 15th. This will be an open alpha test requiring players to use their Facebook accounts to access.
"As some of you rightly mentioned, this is an alpha test, not a full re-opening of the game," Neople cautioned on its Facebook page. "So there might be bits and pieces that don't go as smoothly as we want, and we sincerely hope the DFO community understands this."
[Thanks to everyone who sent in this tip!]