Valve has released the 2015 Compendium to its annual Dota 2 tournament The International last night, and proceeds from its sales have already raised the championship’s overall prize pool to more than $4 million.

First introduced in 2013, the Compendium is a digital interactive program for the competition, where you can keep track of the different teams and make predictions. Each Compendium costs $10, and each sale raises the prize pool by $2.50. As the prize pool grows and hits its stretch goals, more rewards unlock for all Compendium owners and, in some cases, all players. When the Compendium hits $4.5 million, for example, Valve will add new loading screens to the game.

Leveling up your Compendium by using it and completing special challenges will reward you with Battle Point and different items. You can also just buy points to level up, and 25 percent of those sales will also add to the overall prize pool.

Last year, the Compendium helped drive the total prize pool to over $10 million, making it the largest purse for any eSports event in history.

Valve sold tickets to the 2015 International in two waves of 10,000 tickets in late March, both of which sold out in less than 10 minutes.

This year's International takes place August 3-8 at KeyArena in Seattle, WA, the city that's hosted the last three tournaments.