The recent Dota 2 tournament The International 4 was seen by upwards of 20 million viewers, Valve has announced.

At peak traffic, The International was being watched by 2 million people, more than twice last year's audience.

The International was viewable online through a variety of formats, including streams, the game client and through ESPN's own streaming app.

A source close ESPN previously said the massive numbers garnered by The International had convinced the company to move into eSports broadcasting.