Valve has used the grand stage of The International 7 to announce Artifact, an online card game based on Dota 2's world and, to some extent, its mechanics. 

The card game is based on three-lane gameplay, separating it from existing standard collectible card games. Additionally, there are brackets which spawn creeps, players can use five heroes at once, and also get item cards for those heroes. The mechanics difference is necessary, as this is seemingly a reaction to Blizzard's success with Hearthstone, and shows Valve's desire to get into the same arena.

Check out the teaser below and let us know what you think of Valve's first new game in a while. A full explanation of the mechanics can be found in the Youtube archive of The International's stream.