Anonymous has threatened to target Zynga for its "outrageous treatment of employees and actions against many developers" by releasing what it says is confidential information about the casual gaming firm on November 5.
In a post on the hacker collective's official news channel, Anonymous claims to be in possession of Zynga documents detailing plans to lay off 800 employees in a move that would signal the "end of the US game market as we know it".
Anonymous has also released an encrypted data file which it says contains copies of games taken from Zynga's servers. It intends to release the key on Guy Fawkes night unless Zynga ceases its alleged plans to make further layoffs.
Last week Zynga boss Mark Pincus issued a statement confirming the closure of its Boston studio and layoffs affecting hundreds.