Valve has announced that it is now suing Activision Blizzard over the amount of royalties that the publisher has to pay as part of a recent settlement. Valve is seeking to have a court get it about half a million dollars, a sum that could be inflated when legal fees are added. Activision Blizzard has also threatened to counter sue Valve.

The object of the suit is rather complicated. Way back in 2002, Valve, which, at the moment, only developed games and was not interested in publishing, sued then publisher Sierra, in order to get back an undisclosed sum of unpaid game royalties.

The copyright infringement claim led to the termination of the agreement between Valve and Sierra in 2005 but the latter did not manage to pay all the sum, even if it ceded all the rights related to publishing Half-Life, Half-Life 2, Counter-Strike, Counter-Strike: Condition Zero, and Counter-Strike: Source. All the burdens of Sierra are now the responsibility of Activision Blizzard, as part of the merger that took place in late 2007.

Part of the 2005 agreement was that the royalties that Sierra actually owed Valve would be determined by an independent audit arbitrator. Apparently, he only managed to come up with a figure four years later, in 2009. The final amount is 2,391,932 dollars.

Activision has contested this figure, claiming that it has already overpaid Valve by the sum of 424,136 dollars, so it only paid 1,967,796 dollars to the creator of Half Life. But it did so without consulting with the audit arbitrator, so Valve went to court, seeking a confirmation of the initial figure and claiming that Activision Blizzard needed to put up that amount. On the other hand, Activision is saying that its calculations are correct and that it will counter sue if Valve goes ahead with its actions.