Zombies coming to Call of Duty: Warzone is pretty much the worst kept secret in gaming at this point. Following various in-game hints as well as an exceedingly direct tease that came with the content reveal of Season 2, now that the new update is live players have spotted concrete references to the upcoming game mode.

Season 2 launches today in Call of Duty: Black Ops Cold War and Warzone with all sorts of new unlockable cosmetics listed in the game. Among these are a collection of new Calling Cards - small "cover pictures" you can display on your profile - which can be unlocked in various game modes by completing certain challenges.

As of the release of the Season 2 update, Warzone Calling Cards have their own "Zombies" section, with unlock requirements such as "In Warzone, kill 10 Zombies with headshots." You can't get any more direct and blatant than that.

This accidental announcement comes in the wake of fans discovering a Trial Machine lifted wholesale from Zombies inside a Verdansk hospital in Warzone, as well as cryptic messages related to the Vodianoy ship when running through an office in Rebirth Island.

When Treyarch revealed the new content arriving in Season 2, they teased Zombies content in Warzone with a brief blurb near the bottom of the official Call of Duty blog post, stating that a "dark wave" approaches, and that something is rumbling deep below Verdansk.

It isn't yet clear in what way the undead will appear in the standalone battle royale mode, but the tease indicates that underground locations in Verdansk will be opened up - likely bunkers - while the Zombies will arrive to Rebirth Island via the ship. Since this reveal, further audio lines have been discovered in the game reinforcing this:

"Captain Rosental speaking. Russian ship Vodianoy... something happened. We were transporting strange biological material. What have we done?! There was an infection outbreak. I'm afraid we won't be able to contain it."

Get ready for more details and intel regarding the upcoming Zombies mode in Call of Duty: Warzone!