Defense of the Ancient's path from an ultra-popular Warcraft III mod to the core of Valve's ultra-popular MOBA, Dota 2 is a long and confusing saga. Now, two developers working on their own mobile versions of Dota are arguing in court that Valve didn't actually acquire a legitimate, enforceable copyright that encompasses the entirety of Dota's development history. This question now seems set to go to a jury.

The history

Federal Judge Charles Breyer of the Northern District of California lays out an excellent summary of Dota's development history in a recent ruling denying summary judgement for Heroes Charge developer uCool. Breyer explains how Dota started life in 2002 as a Warcraft III mod made by Eul (real name: Kyle Sommer), who created the mod on his own and thus holds the rights to the "setting, heroes, rules, and name."

From there, in 2003, modders started to take "the best, most enjoyable characters from all the other version of Dota" and split off a new version of the mod called Dota All-Stars. A modder going by Guinsoo (real name Stephen Feak) soon took over this branch of the project, accepting and coalescing contributions from the modding community (unlike Eul, who largely worked alone).

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By 2005, lead development of Dota All-Stars had transferred to IceFrog (real name: Abdul Ismail). After a brief stint with S2 Games to work on the Dota-like Heroes of Newerth, IceFrog was hired by Valve in 2009. In 2010, he sold Valve his rights to Dota 2 "for a handsome price," as the ruling puts it. Valve later also hired Eul and acquired his rights to the game as well.

Guinsoo, meanwhile, was hired by Riot, which was working on the Dota-like League of Legends. Riot bought Guinsoo's claim to the Dota copyright and sold it in turn to Blizzard. To avoid any clashes over the Dota name, Blizzard and Valve settled out of court in 2012. Valve would retain the rights to the name for standalone games like Dota 2, while Blizzard could use it to refer to Warcraft and Starcraft mods specifically (a project then called "Blizzard Dota" would eventually become Heroes of the Storm).

Dota is not a "collective work"

This history is getting hashed out in court because Valve and Blizzard are now suing mobile developers Lilith and uCool, whose respective games Dota Legends and Heroes Charge allegedly infringe on the Dota copyrights.

In court, mobile developer uCool tried to argue that Dota All-stars is a collective work, because it "took the most popular Dota heroes and arranged them into a new game." Judge Breyer rejected that argument, saying that "by that logic, Star Wars: The Force Awakens would be a collective work because it arranged the most popular Star Wars heroes, settings, and one-liners into a new movie."

Instead, Breyer determined that "the record contains ample evidence that Eul, Guinsoo, and IceFrog were the masterminds behind their respective versions of Dota and Dota All-stars." Even though they took inspiration from other sources and suggestions from other contributors, these three "decided which [contributions] made the cut."

In this way, the modders in question are much like a director or screenwriter who consults experts for help with a movie. "So just as Spike Lee was the author of the work at issue [in a case surrounding Malcolm X], a reasonable jury could (and perhaps must) conclude that Eul, Guinsoo, and IceFrog are the authors of the various works at issue here," Breyer writes.

Is Dota actually open source?

But that's not the end of the case. For one, the original EULA for Warcraft III says mod-makers can't use the game's World Editor "for commercial purposes including, but not limited to, distribution of [mods] on a stand-alone basis or packaged with other software or hardware." Though uCool has yet to make this argument in court, Judge Breyer says that Eul and IceFrog's eventual sale of the Dota copyright to Valve "seems as commercial as uses go."

(The Warcraft III EULA doesn't give Blizzard any rights to the mods made on top of the game. If that EULA had been written a bit differently, Blizzard could have taken easy ownership of what is now one of gaming's most valuable brands).


The case could also take an interesting open source-based turn thanks to a September 23, 2004 forum post that could be seen as Eul giving up his claim on any rights to Dota. "From this point forward, Dota is now open source," he wrote. "Whoever wishes to release a version of Dota may without my consent, I just ask for a nod in the credits to your map."

This post "might mean that anyone had permission to build their own versions of Dota on any platform—and to sell their versions of Eul’s creation," as Breyer puts it. Or it might simply mean that Eul was just granting a "limited license" intended for other mod-makers, not for standalone games based on Dota.

"What is more, a reasonable jury could also conclude that the word 'whoever' referred only to the motley group of modders making up an informal Dota online community," Breyer continues. "Eul’s post, in other words, was aimed only at fellow teenagers building fantasy worlds for fun—not companies exploiting them for financial gain. So uCool was arguably no licensee at all."


With summary judgement for uCool denied, the case now seems set to continue to a jury, which will have to interpret all of this history to determine whether Valve's claim to Dota is valid. If it's not, we could see dozens of Dota spin-offs flooding the market to capitalize on the game's pedigree. We'll keep an eye on the case as it progresses and keep you posted as new developments arise.