Last week, Square Enix showed off some of the world where Final Fantasy XV takes place. It looks huge. As you can see in the video, you can freely explore the field. If you like, you can can stop at gas stations and rest. When running in the field, your party members get tired and stop as would real people.
If you get too close to the creatures, you'll have to fight them. There are other animals, like cats and birds, that are smaller. You can wander through the forest and climb hills and mountains. There are Chocobo you can ride. You can fish in the lake. You can walk or go anywhere you can see.
The number of active monsters increases at night, so it's best to take cover at a place like the gas station.
What was shown is featured in the Episode Duscae demo, and it is ten per cent (１０分の１) of the entire Final Fantasy XV field. The demo will be available with Final Fantasy Type-0 HD, available in March 2015.