No experience with eSports, but hey I'll give my two cents.
No clue. If I had to guess, Last Competitor Standing, Extreme Championship Sports, OverWatch, and 4-pool stand means a bracket of four teams vying for first, second, third, and fourth places.
Something that connects them? From my perspective, it's the teamplay dynamic that those games encourage. In each situation and game, it's all about being able to rely on your teammates. As they say, a chain is only as strong as its weakest link. Everyone in an eSports team is presumed to be a professional in their own right, so teams and its members must be strong. It makes it intense in the sense that every player on the team has to pull their weight through the game. Any one teammate dropping the ball can cost the game for their team. It appears to be rather stressful, honestly.
What I find interesting is how much attention eSports gets. I've seen bits and pieces on social media of channels covering various gaming events. Do note, the regular sports channels air NFL football games, NBA basketball matches, and even golf tournaments, which makes it interesting to see some channels accept eSports as a part of the competitive scene and televise it on their networks. And the crowds, even! When you see these events as they happen, it's impressive the many people you'll see in attendance.
eSports is quite a culture, and one that seems to be growing in mainstream popularity. A child today can say they wish to become an eSports competitor as their future career, and it's very much viable! There's a sense of fame to it, and money to be made from it!
/$0.02