Will Square Ever Re-Run A Collaboration?

[Enkidoh]

The FFXIII event's whole purpose was actually for LR:FFXIII - it was run to coincide with LR:XIII's release at the time (LR:XIII in turn features a sidequest that rewards miqo'te starting armour and you can can also get the level 50 Grand Company swords for Lightning too) - you could also see this with some of the weapons offered with the FFXIII event in FFXIV were actually from FFXIII-2 and LR:XIII (Serah's bow and Mog's staff from XIII-2, and the crystal/ice axe Snow used in LR:XIII). Which is the important thing to remember about the crossover events.

Each game that has had a special event run in FFXIV, also has a special FFXIV-themed event or special FFXIV-connected sidequest in the other title in turn: FFXI has a special event featuring Eorzean spriggans appearing in Vana'diel (and the second FFXI event in FFXIV coincided with the 'Rhapsodies of Vana'diel' storyline officially completing FFXI's main scenario, hence the FFXI event in FFXIV featured that storyline's main NPC Iroha appearing mysteriously in Hydaelyn), and in FFXV there is a permanent sidequest that involves a miqo'te ACN from Hydaelyn appearing in Eos along with a bunch of ixal who try to summon Garuda, which ties in with the FFXV event in FFXIV.

Hence, no new events for other FF games I'm afraid (although a FFVII-themed special event has long been rumoured, nothing has come of it sadly).