The "surprise Sony sequel" - due to be revealed tomorrow - is not Resistance 3, Insomniac has confirmed.
In a post on popular game forum NeoGAF, senior community manager James Stevenson said that he knew the identity of the mystery game, but confirmed it wasn't an Insomniac title.
Elsewhere, the Resistance and Ratchet & Clank developer has revealed it is working on more than one game.
Speaking in an update on the developer's official website, senior community manager James Stevenson said Insomniac is working on "some really cool stuff that we can't wait to show you".
Stevenson said: "After the launch of A Crack in Time, there was some well-deserved time off for folks. We began to ramp up on other projects, and are currently underway on more than one game right now (which will be no surprise to anyone who knows how our production pipeline works). We've been trying to evolve our production pipeline to give us more time for iteration, as well as better efficiencies along the way."
He added: "We hope to eventually be able to share some of these tidbits (when things are farther along), but it's pretty awesome to see a bunch of e-mails on Friday detailing new progress, with art, screens and video to show off what's going on. It's been really exciting to see our future projects take form."
Could one of the games Insomniac is working on be Resistance 3? In October last year a billboard advertisement for Resistance 3 was spotted on the film set of what was believed to be Battle: Los Angeles.