When Valve launched the Interactive Compendium for DOTA 2's The International, it made a promise to players who purchased the book to unlock new fetures for them whenever the sales reached certain milestones.
Today, the game has reached over $250,000 in sales, all of which will be added to The International's prize pool to give away to skilled players who win the competition.
The developer says that their original plan was for the International 2013 Courier to be able to ride a small set of mounts, and now the art team knows the community demands more. To that end, they have posted some concepts for some of the new mounts they now have on the to-do list:
Given the popularity of the Interactive Compendium, Valve is planning to add even more stretch goals to give goodies away to players.
If you'd like to participate, you can buy the Interactive Compendium here.