„We'll take a look at more than 2 million games, taken from the MillionBase PGN database […] total there are 2,197,113 games […] spanning […] from 1801 up to 2013.“ Here's the „Opening Tree“:
Like many other amateur players, I tend place more importance on openings than I probably should. That being said, I was really excited about seeing the opening tendencies and popular moves. [Above] is a visualization of the first 5 moves (10-ply) from every game.
Right from the first move, I see that e4 dominates by a large margin (48%), followed by d4 (34%). […] Of course, among e4 openings, the beloved (and my favorite reply as Black) Sicilian (c5) is the most common reply, even more than e5. 2. Nf3 is by far the most played as White, aside from some respectable chunks from Alapin and Closed Sicilian. Interestingly, Black's second move seems to be a very critical crossroads of how the game will play out.