https://techcrunch.com/2017/11/03/starcraft-ii-will-be-free-to-play-starting-november-14/

It was only in April that Blizzard made the original StarCraft free to play, and now the company has done the same for its sequel. StarCraft 2: Wings of Liberty, which is certainly the most-played real-time strategy game ever made, will be free for anyone to play starting on November 14. Of course there’s a catch, but nothing nefarious.

The game was really divided into three episodes, each focusing on one of the three playable races (Human, Zerg, and Protoss — but you knew that), and only the first (the human one) will be available for free. Be aware however that you need to log in and claim it before December 8.