As some may remember, Valve and publisher Sierra were in a heated court battle for years. The two finally settled the case, where Sierra was to pay Valve royalties of $2.4 million, however, during the court battle, Sierra was taken over by Activision, who took over the debt to Valve.

According to a case filed by Valve last week in the US District Court for the Western District of Washington, Activision owes Valve another $424,000 — an amount Activision clams it withheld because it paid more in royalties on other occasions. Valve thinks otherwise, and wants an additional 1% in interest per month, plus lawyer fees.