The project, revealed in job listings spotted by Andriasang, is in development at the publisher's 1st Production Department, responsible for the Final Fantasy and Kingdom Hearts games.
One listing calls for a planner, tasked with work "related to player growth and customisation, including job properties, ability properties, [and] a growth system." Another listing calls for "creating play elements for flying an airship over a world map" and for gameplay elements within the airship itself.
The news is further evidence of Square Enix's increasing preference for thirdparty development solutions following the announcement last month of a multi-project Unreal Engine 3 licence. Last week it was revealed that Dragon Quest IX co-producer Ryutaro Ichimura is heading up development of an action-RPG using Epic Games' engine.