John Carmack, the chief technology officer of Facebook-owned Oculus, sued ZeniMax Media on Tuesday, saying it still owes him money from buying the video game studio that he founded.

Carmack says that ZeniMax owes him more than $22.5 million and refuses to pay because of "sour grapes".

ZeniMax bought id Software, a Richardson-based video game studio, in 2009 and Carmack left the company in 2013 to become Oculus' CTO.

ZeniMax agreed to pay $150 million for the purchase but eight years later it has refused to pay the final installment of cash it owes Carmack or let him convert it into shares of stock.

At the time of the sale, the lawsuit says Carmack was the majority shareholder of id Software and received a convertible promissory note valued at more than $45.1 million. He converted half of that into shares of ZeniMax stock, which he received.

The lawsuit asks the court to compel ZeniMax to pay the other half that it owes Carmack, according to the terms of the sale.

ZeniMax told the press that the claims are "completely without merit" and noted that a court had rejected a previous claim by Carmack that ZeniMax had violated his employment agreement.

"Apparently lacking in remorse, and disregarding the evidence of his many faithless acts and violations of law, Mr. Carmack has decided to try again," the statement said.

The lawsuit filed by Carmack says that ZeniMax won't pay the remaining sum for id Software because of the intellectual property lawsuit -- but it notes that the jury did not find Carmack liable for misappropriation of trade secrets or copyright infringement.

"ZeniMax's invocation of the same alleged acts that it just went to trial on is an exercise in bad faith and distraction, not a legitimate basis to avoid paying the money it owes from its purchase of id Software," the lawsuit says.