Blizzard's survival game has been in development for almost 5 years

pcgamer.com:

Blizzard clearly isn't ready to share many details about its upcoming survival game, because the only title for the game it's given us is «Unannounced Survival Game.» Enigmatic! The non-announcement has at least allowed current and ex-Blizzard developers to speak openly about their involvement, and based on their comments, we've learned that: A) people with knowledge of the project are pretty hyped about it, and B) it's been in some form of development for more than four and a half years.

Unannounced Survival Game's development is being led by Craig Amai, who said on Twitter that the game started as a «humble pitch» on his PC. According to Amai's current LinkedIn profile, he left the World of Warcraft team and started leading the survival game team in July 2017, four years and seven months ago.

Amai has had a long career at Blizzard. According to his resume he joined the company in 2004 as a senior game master who offered «varying capacities of in-game customer support, primarily for World of Warcraft.» He later became a senior designer on WoW, and then lead quest designer, working on the MMO all the way until he started on the survival game he pitched in 2017.

We also know that the survival game is in a playable state, because Blizzard boss Mike Ybarra said on Twitter that he's «played many hours» of it with the dev team. A smaller detail I noticed today is that Geoffrey Virtue, executive producer of Teamfight Tactics at Riot, co-led Blizzard's survival game between 2019 and 2021. 

«This is a project that will have a big impact on the industry,» Virtue said of the game this week.

This July, Blizzard's survival game will have been in development for five years, but we don't know how much of that time has been spent