Even at that peak number, the game likely isn't the most popular overall. Even in 2014, Riot Games' League of Legends had as many as 7.5 million people playing at once. Newer daily numbers don't appear to be available, but it's safe to say that number isn't likely to have dropped much or at all.

It's not hard to see why PUBG might eclipse its Steam rival, at any rate. It has an easy-to-grasp concept (make sure you're the last one standing) that makes it more accessible than a daunting game like Dota 2, and it's practically tailor-made for competitive players and streamers. It's the second most popular game on Twitch after (you guessed it) League of Legends, and it's well ahead of Dota 2. Simply put, more people can get into PUBG, whether they're playing or watching from the sidelines.