Erik Lindqvist's LinkedIn Page has a credit for a game called Fortress that was being developed by now defunct GRIN for Square Enix before being cancelled. This comes way of superannuation, who also show us that Tomislav Spajic's LinkedIn Profile lists an "unannounced Final Fantasy project" on his résumé that is also Fortress, as his portfolio offers art from Fortress as well as Cult, "another cancelled and unannounced project." You may want to hurry to check out the art if you're interested, as they also link to a portfolio that's already been deleted.