Here is an overview of the game, via Square Enix:
Dissidia Final Fantasy NT Free Edition offers players the opportunity to try out a limited roster of characters on a weekly basis. A variety of characters and weapons are also available for individual purchase. This ensures that favorite characters can be a permanent member of a player’s roster. Players of the free edition can also play online against existing players of the full game.
Developed in partnership with veteran fighting game studio Team Ninja from Koei Tecmo Games, Dissidia Final Fantasy NT is a unique three-versus-three team-based brawler, where players work together to overcome their rivals and dominate the battlefield. Featuring legendary characters from throughout the Final Fantasy NT series, powerful summons, online and offline play modes, character skins, and a new original story, Dissidia Final Fantasy NT welcomes players of all types to enter the arena. With Dissidia Final Fantasy NT Free Edition, players can enjoy a sample of the full game and discover the epic multiplayer encounters only available in its unique online arena.