At that point, however, Newell had yet to give Dota 2 the thumbs up. It wasn't until Adrian spent a week building a proof-of-concept prototype, exploring the DOTA camera perspective and mechanics in Valve's own Source engine just to see if the game was feasible, that Dota 2 became a reality. "He just did it on his own initiative," Gabe says. "That's the sort of thing that causes us to make a decision.
"I have no idea what the costs are, or the profitability that's projected to be of Dota, because nobody's ever bothered to figure it out. For good or for ill, that's just not how we make decisions."
Dota 2, like Team Fortress 2, began life as a fan project, but it is now a fully-fledged Valve venture with a 60-strong team (the same size as the Half-Life 2 and Portal 2 teams) tweaking item balance and map design for its projected 2012 release.
That seems an excruciatingly long way away, particularly for a game that appears to be in such rude health (Gabe and Erik admit there are issues still to be resolved, including a mysterious lag problem that is currently affecting matches). Although press and public aren't being allowed to play the game yet - we'll report back in detail when we get access to the beta soon - the Gamescom tournament is providing DOTA veterans with plenty of concrete information. Replay videos are already on the internet. Experts are filling forums with discussion on the heroes' strengths and weaknesses. Players are already plotting strategies, contemplating set-ups and, generally, getting pretty excited about Valve's first foray into fantasy.
But where is IceFrog? On the day Dota 2 is revealed to the world, on the day thousands of gamers at Gamescom and on the internet are watching the first Dota 2 tournament ever, shouldn't the mysterious modder be around to take it all in?
"He's very shy, actually," Gabe notes. "Super smart. Super analytical. Very focused. Once he gets over being nervous, because he is shy, then he could start talking about game design and game decisions.
"It's just drinking out a firehose. He fits right in with everybody else. He's fun to work with; a good collaborator. It was easier for us to adapt to him than the other way around, because he really hadn't had the experience of working with other people for the last few years. So for him it was like, who are all these people? There are so many people! They're everywhere!
"But he's having a lot of fun and pretty excited to see what's happening with Dota 2."
Funny that. So are we.