Engadget has details from a WSJ.com article describing a formal notification sent to Oculus VR by ZeniMax declaring ZeniMax's belief that Oculus is using technology that belongs to them, saying it was developed by John Carmack before he left ZeniMax to join the virtual reality startup. ZeniMax gave them a statement saying: ""It's unfortunate, but when there's this type of transaction, people come out of the woodwork with ridiculous and absurd claims. We intend to vigorously defend Oculus and its investors to the fullest extent," and Carmack also replied via twitter, saying: "No work I have ever done has been patented. Zenimax owns the code that I wrote, but they don't own VR." They also have a statement from ZeniMax:

ZeniMax confirms it recently sent formal notice of its legal rights to Oculus concerning its ownership of key technology used by Oculus to develop and market the Oculus Rift. ZeniMax's technology may not be licensed, transferred or sold without ZeniMax Media's approval. ZeniMax's intellectual property rights arise by reason of extensive VR research and development works done over a number of years by John Carmack while a ZeniMax employee, and others. ZeniMax provided necessary VR technology and other valuable assistance to Palmer Luckey and other Oculus employees in 2012 and 2013 to make the Oculus Rift a viable VR product, superior to other VR market offerings.

The proprietary technology and know-how Mr. Carmack developed when he was a ZeniMax employee, and used by Oculus, are owned by ZeniMax. Well before the Facebook transaction was announced, Mr. Luckey acknowledged in writing ZeniMax's legal ownership of this intellectual property. It was further agreed that Mr. Luckey would not disclose this technology to third persons without approval. Oculus has used and exploited ZeniMax's technology and intellectual property without authorization, compensation or credit to ZeniMax. ZeniMax and Oculus previously attempted to reach an agreement whereby ZeniMax would be compensated for its intellectual property through equity ownership in Oculus but were unable to reach a satisfactory resolution. ZeniMax believes it is necessary to address these matters now and will take the necessary action to protect its interests.