http://www.pcgamer.com/overwatch-is-free-to-try-this-weekend/

Blizzard announced that Overwatch was free to try this weekend last week, and Andy reported on it here. But whose memory stretches back a full eight days? Consider this a reminder, then, and know that Endless Space 2 and Rainbow Six: Siege are also running complimentary opt-in periods over the next few days. 

Speaking to Overwatch, though, the promotional window runs from today through Monday, November 20, with the game's full roster of 26 heroes and 16 maps available to all across the game's Quick Play, Custom Games and Arcade modes. Progression and loot boxes will also be active throughout—with the former carrying over, should you decide to splash out for the game in full thereafter.