Indirect DOTA co-creator Blizzard has legally opposed the Dota trademark Valve is trying to register for new game Dota 2.

"By this Opposition, Blizzard seeks to prevent registration by its competitor Valve Corporation of a trademark, DOTA, that for more than seven years has been used exclusively by Blizzard and its fan community, under license from Blizzard," stated Blizzard.

"By virtue of that use, the DOTA mark has become firmly associated in the mind of consumers with Blizzard, including to signify a highly popular scenario or variant of one of Blizzard's best-selling computer games, Warcraft 3."

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"By attempting to register the mark DOTA," Blizzard went on, "Valve seeks to appropriate the more than seven years of goodwill that Blizzard has developed in the mark DOTA and in its Warcraft 3 computer game and take for itself a name that has come to signify the product of years of time and energy expended by Blizzard and by fans of Warcraft 3.

"Valve has no right to the registration it seeks.

"If such registration is issued, it not only will damage Blizzard, but also the legions of Blizzard fans that have worked for years with Blizzard and its products, including by causing consumers to falsely believe that Valve's products are affiliated, sponsored or endorsed by Blizzard and are related or connected to Warcraft 3."

Blizzard's opposition was filed on 16th November.

Valve responded on 22nd December.

The bulk of the responses state that, "Valve is without knowledge or information sufficient to form a belief as to the truth or falsity of the remaining averments of this paragraph and, therefore, denies same."

Valve stopped short of acknowledging that DOTA (Defence of the Ancients) began life as a Warcraft 3 mod. But Valve did accept that Blizzard shipped a World Editor with Warcraft 3 that allowed fans to make "mods".

Both Blizzard and Valve are now making DOTA-inspired games. Blizzard DOTA will be a StarCraft 2 mod; Valve's Dota 2, built by DOTA creator IceFrog and team, a new game. Both are expected this year.