PC games giant Valve apparently shifted 149,000 units of its Index virtual reality headset in 2019.

That's according to research firm SuperData, which reports that the company sold 103,000 of these during the last quarter of 2019. Sales of the Index VR headset are said to have doubled between Q3 and Q4 owing to the company announcing virtual reality exclusive Half-Life Alyx.

Oculus Quest, meanwhile, sold 317,000 units during Q4, ahead of the Oculus Go, which shifted 84,000 copies, and the Oculus Rift S which was bought 71,000 times. The Quest wasn't the most popular VR headset for the quarter, however; that title goes to PlayStation VR, which hit 338,000 sales during the three-month period. Sony's kit also had a huge marketing push during the Christmas period. 

Valve Index was announced in May 2019 before a June launch. Half-Life Alyx was first shown to the public in November to a huge amount of excitement. The firm has insisted that the game isn't going to be delayed and has made all other entires in the Half-Life franchise free to buy on Steam.

Half-Life Alyx has also helped Index sell out around the world, with the hardware only available in Japan in the middle of January.