The feud between Oculus and ZeniMax Media is opening up once again, this time with the CTO of Oculus, John Carmack, suing his former employer for earnings that he claims are still owed to him.

The suit is largely unrelated to the $6 billion trade secrets suit which ended last month with a $500 million judgment against Oculus. Instead, Carmack is suing ZeniMax Media for $22.5 million that he says has not been paid to him for the 2009 sale of his game studio, id Software, known for such pioneering video game classics as Doom and Quake.

The lawsuit reveals that ZeniMax Media paid $150 million for the game studio.

The document details that Carmack was set to earn $45 million from the id acquisition. In 2011, Carmack converted half of that note into a half-million shares of ZeniMax common stock, but has yet to receive the other half of his earnings in cash or common stock from the company, despite formal requests being made.

Carmack stayed on at ZeniMax Media, a game publisher behind such titles as Skyrim, until late 2013 when his contract expired, at which point he joined Oculus VR as its CTO.

In the suit, reported first by Dallas News, Carmack claims ZeniMax Media has not paid the remaining sum due to, what the suit calls, “a series of allegations regarding claimed violations of Mr. Carmack’s Employment Agreement,” this assumedly relating to ZeniMax’s suit against Oculus regarding the theft of trade secrets.

ZeniMax, however, never brought charges of breach of contract against Carmack in that lawsuit, and Oculus was not found guilty for stealing trade secrets. The judgment was instead levied against Oculus and two of its founders for copyright infringement, false designation and the violation of Palmer Luckey’s NDA.

Carmack’s suit claims “sour grapes” on ZeniMax’s part in not paying back the money he says he is owed, something that has caused Carmack “serious injury” to the tune of more than $22.5 million.