Rather than turn-based menu fighting during the battle scenes, it seems that once your decisions are set the tide of the battle is based on button combinations you press in time - and when you get it right, a message like "perfect" will appear on the screen.
Eventually, the enemy side brought in a huge birdlike creature - and Rush retaliated by using a pendant to summon a Remnant - Cyclops. Morale, represented by a gauge at the top of the screen, had been very low when the bird flew in. It shot up to 100% for the allies and 0% for the enemies once Cyclops entered the battle, however. Cyclops appeared to be a traditional FF-style summon attack - you aren't commanding but just watching. A large magical cannon began to activate - but before we could see what happened, the demo ended.
According to Takai, since "the battlefield is linked to the overworld map, wandering enemies can join the battle freely. Players who go easy can find themselves in trouble." The background music will also change depending on how the battle is going. Fighting well will encourage your allies to fight - that accounts for the moral gauge - and make the enemies falter, "which makes a big difference." He finished by saying "Despite the tried and true command system we think that gamers will be in for a truly new experience."