The battle between Oculus and video game company Zenimax over who created the technology for the virtual reality headset Rift finally dragged Facebook Founder Mark Zuckerberg into the picture.

Zenimax said it and id Software, the company behind Doom, "welcome the opportunity" to present what it claims is "substantial evidence" against Facebook and Oculus in the case. ZeniMax is also ready to present evidence of the defendants' intentional destruction of evidence.

The company, which owns games developer id Software, is reportedly suing Facebook for $2bn, claiming that Oculus copied its early innovations in VR when developing the Oculus Rift headset.

Facebook's acquisition of Oculus was vetted in a matter of days, CEO Mark Zuckerberg revealed in testimony on Tuesday.

"We're eager to present our case in court", a spokesman for Oculus said. Zuckerberg made a decision to buy Oculus after a demonstration earlier that year, and has since said he believes VR will change the way we interact with computers.

A lot of lawsuits come and go without most people hearing about them, but the current one between ZeniMax and Oculus has recently had good reason to pop up on news sites.

Oculus founder Palmer Luckey, who has gone off the radar after it emerged he had funded an online troll campaign in support of Donald Trump, is also expected to be called to the stand this week. In particular, Zuckerberg seems to have been unaware of Luckey's non-disclosure agreement with Zenimax, which includes a clause forbidding him from using the proprietary information to gain a competitive advantage against the company. Oculus and its founders have invested money and time in developing VR with the aim to fundamentally transform the way people interact and communicate, that statement says.

A reportedly testy Zuckerberg got snappy when the plaintiff's lawyer questioned him about why Facebook purchased Oculus without allegedly pursuing due diligence.

During an interview with USA Today in 2014, Carmack said, "When it became clear that I wasn't going to have the opportunity to do any work on VR while at id Software, I chose to not renew my contract". Also, Oculus reps expressed disappointment at the "wasteful litigation" used by another company to "take credit".

This June 11, 2015, photo, shows the new Oculus Rift virtual reality headset on display.

Facebook acquired Oculus for 2 billion dollars, and ZeniMax is seeking an amount in the same neighborhood in damages. Luckey, another defendant in the lawsuit, hasn't testified yet.

It'll be interesting to see how it all ends, and what details see the light of day the next three weeks.