Gameplay Mechanics
No matter how visually impressive a game is or how compelling the concept may be, it all relies heavily on the gameplay it brings to the table. The purpose of demos on previous console generations was to determine if a game was fun to play or not. The same applies to a modern day beta. At the end of the day, the player will be given a focused example of what it is like to actually play the game.
Was it fun? Did the shooting mechanic feel sharp? Were the controls logical and easy to adapt to? Does the game feel like an RPG with shooter mechanics thrown in, or a third-person shooter with some elements of roleplaying?
Already, there have been some questions about a design choices within the game, such as the amount of damage an enemy requires to be killed. In the beta, the player will decide for themselves whether or not these gameplay decisions fit in the universe created.