Rather than wait until the end of The International, the major Dota 2 tournament taking place in Seattle all week, to announce major Dota news, Valve surprise-announced an entirely new video game on the event's second, early-rounds evening.

"It's not Half-Life 3," broadcaster Sean "Day9" Plott said, and he insisted that the game was not a re-release or a fine-tuning of an existing game à la Counter Strike: GO or Dota 2. Then, he introduced a vague, 35-second teaser video that prominently featured a triangular logo. It ended with the phrase: Artifact: The Dota Card Game, which Valve says will publicly launch sometime in 2018. (Technically, Plott wasn't lying, but gosh, did he come close.)

Sadly, Artifact's reveal was not followed with anything in the way of screenshots or gameplay. Instead, Plott described having played test versions of the game already, and his brief description hinted at a one-on-one digital card-battling game, like Hearthstone, only with a Dota-themed three-lane system and other Dota-like tweaks.

"I played a game where I was getting my ass kicked in two lanes," Plott told the bemused crowd. "I kept building barracks in the third [lane], and I kept flooding the lane with creeps." What Plott didn't tell the crowd was that this is the game developer Brad Muir has been leading at Valve since he left Double Fine (where he previously led development on the tactical RPG Massive Chalice and the co-op tower-defense game Trenched).

We'll have to wait for more information on Artifact's card-based systems, like spells and movement cards, and whether or how players will juggle the Dota series' hundred-plus roster of heroes. We're also still waiting to hear about Valve's other games in the oven, especially following promises of three bespoke virtual reality games in development.