This is indeed on PS4, PC and Xbox One, so if you are a console user, use the search function on the marketplace and you will probably find it if you type in 'Overwatch'.
If you haven't heard of Overwatch, it is a first person shooter created by Blizzard. What's the difference? It features 21 different heroes, with different abilities, creating different composures and styles of gameplay.
The download size for the beta doesn't seem too bad, PC is roughly around 6.5GB, I am not sure about the console releases, but I assume it is roughly the same.
Still not too sure about it? Take a look at this video and try the beta whilst it is free!
The final product of the game will come out on the 24th. If you haven't pre-ordered yet, you may do so here.