https://www.techradar.com/news/heres-how-to-play-overwatch-for-free-this-weekend

Overwatch, Blizzard's team-based shooter, is free to play this weekend on PC, Xbox One and PlayStation 4. 

The game can be downloaded and played for free for a limited time, from August 23 through August 27. During this free period, you can access everything Overwatch has to offer, including all 28 heroes, 18 maps, quick play, custom games and arcade mode. You can even level-up and earn loot boxes.