The International, Valve's Dota 2 tournament, has just crossed $15 million in prize money. In comparison, 2014's tournament raised almost $11 million.

The International raises money for its prize pool through crowdfunding. Valve, the developer of Dota 2, sells an in-game collection of items, called the Compendium, for $10. A quarter of each Compendium sale goes into the prize pool. Valve itself contributed $1.6 million to start the pool, so players have been responsible for over $13 million.

This also means that Valve is making a lot of money on sales of the Compendium, receiving 75% of each purchase.

The International 2015's prize pool blew past last year's total, which itself was the largest esports prize pool ever. The prize money for this year's tournament exceeds the pool for the 2015 Masters golf tournament, which was only $10 million.

As of now, every single sales goal for the Compendium has been met; the last one was unlocked at the $15 million mark. Valve may create new stretch goals, but for now everything possible has been unlocked by the community. These in-game items are available to everyone who owns a Compendium, and they include couriers, weather effects, and announcers.

When the 2015 Compendium first went on sale, it raised $4 million in its first night, and went on in June to break the record for the biggest gaming reward ever. The International takes place August 3-8 at Seattle's Key Arena, but tickets for the event sold out within ten minutes.