The first video demonstrates some of the new underwater features that Bohemia Interactive are working on, showing off the new sound effects, and graphical details to make the environment as realistic as possible.
The second video takes up to the skies to show some of the terrain from above and the coastal towns that they are working on. The final video below shows a presentation of the combat.
New features include ragdoll physics, physics enabled vehicle handling and environmental objects, diving, weapon customization, and new types of land mines such as bouncing betties.
View this and more from Gamescom at the Arma3official youtube channel.