id Software will reveal a new game at QuakeCon tonight.
id founder and technical director John Carmack said on Twitter that id will announce a brand new game at QuakeCon, which is due to kick off at 8.30pm UK time tonight.
"I'm showing something neat and unannounced at quakecon tomorrow. Deciding if I should leave it be or sneak a little more code in..."
Elsewhere, Carmack told the Official PlayStation Magazine (reported by TVB) that Doom 4 shouldn't take as long to get out the door as its other shooter Rage is taking.
"We've got Doom 4 going on right now below our feet here," he said.
"The Doom team are all sped up and working on this technology base I'm not really at liberty to discuss much about it, but it's going full steam ahead right now.
"It shouldn't take as long to ship as Rage. It's already in the pipeline and we feel good about it."
Rage is due out next year.
What do we know about Doom 4?
In August last year id Software boss Todd Hollenshead said the developer will talk about Doom 4 in more detail at QuakeCon 2010, so expect a proper reveal tonight.
"When we show it to you you're gonna love it," he said.
Doom 4 was first announced in 2008 when id started seeking people to begin work on it. Hollenshead has denied it would be a sequel, but said it wasn't a reboot either.
Carmack told Eurogamer that Doom 4 will be "three times" the visual quality of Rage thanks to its 30fps frame-rate (Rage runs at 60), and that it may "leverage some of the Quake Live infrastructure" for multiplayer.