Dota 2 was first made available to the public at Gamescom in 2011.
Valve revealed the game at Gamescom in Cologne, Germany, alongside the first International championship. During the event, Valve began sending closed-beta invitations to selected DotA players and attendees, giving the public its first opportunity to see and access the successor to the popular Warcraft III mod Defense of the Ancients.
Gamescom was particularly significant because it combined Dota 2’s public debut with a major esports showcase. Sixteen teams competed in the inaugural International, allowing spectators to see the unreleased game played at a high competitive level. This is why the event is sometimes remembered both as a trade fair reveal and as the birthplace of Dota 2’s professional tournament scene.
The public-access milestone should not be confused with the game’s full release. Dota 2 entered open beta in September 2011 and was officially released on Steam for Windows on July 9, 2013. PAX Prime hosted a later International, but not the game’s first public availability.