That represents a delay of a few months — when Guerrilla unveiled Horizon Zero Dawn at E3 2015, the studio said it planned to release the PlayStation 4 exclusive in 2016.
"It wasn't an easy choice to make; we know many of you have been anxious to play the game since we first announced it," said Hermen Hulst, Guerrilla's managing director, in a PlayStation Blog post. "However, we also want to ensure that Horizon Zero Dawn lives up to the visuals and gameplay quality that our games are known for. The new date affords us the extra time required to deliver fully on our ambitious vision for Horizon Zero Dawn."
On the bright side, Guerrilla released a new Horizon Zero Dawn trailer alongside today's delay announcement. The three-minute video focuses on Aloy, the game's protagonist; you can watch it above. For more on Horizon Zero Dawn, check out our E3 2015 write-up of the game.