A rumour has surfaced that Halo 4 is already in "full development" over at Bungie.

This comes from an anonymous sources who have spoken to the sarcasticgamer site.

If there isn't another 'proper' Halo game at some point (other than a spin-off like Halo Wars) SPOnG will eat its face. That said, we're struggling with this rumour. Why? Bungie's head writer, Frank O'Connor, recently quit Bungie to work "more closely with Microsoft on the Halo franchise." If he wants to be as close as possible to the Halo franchise, why leave the company that is developing the next game in the series?

Also, sarcasticgamer claims in its article that 20 million copies of Halo 3 have been sold. Last we heard (in April) only 19 million Xbox 360s had been sold. Granted, that number could be up to 20 million by now, but we struggle to believe that every single Xbox 360 owner has bought a copy of Halo 3 and Microsoft hasn't bothered to cry it from the rooftops.

We're keeping an open mind.

^{Source: sarcasticgamer.com}