The website contains no details or description of the project and only displays what appears to be a date (1.17) and silhouettes of behemoths from Final Fantasy 6.
The website's URL also contains the letters "ff_atb". ATB could potentially refer to "All The Bravest", which is the name of a domain Square Enix trademarked in 2012. ATB also stands for Active Time Battle in Final Fantasy terms and was a battle system that debuted in Final Fantasy 4 and was used in some form in subsequent Final Fantasy games.
Judging by the teaser website, more information is expected to be available Jan. 17.