The agreement will see Masthead co-developing Project V13 with Interplay's internal teams under Interplay's direction and control, and implementing tools and technology that Masthead created for Earthrise--a post-apocalyptic MMO due out later this year.

When Interplay sold the Fallout property to Fallout 3 develop Bethesda they retained the rights to create an MMO, assuming it could began development by April 2009. Unsubtle clues that Project V13 is indeed Fallout include this piece of concept art, by artist Natiq Aghayev, which references Fallout's own in-game brand of fizzy pop, Nuka Cola.

Jason Anderson--one of the original Fallout's original designers--had been working Project on V13 but left last month to develop a new RPG for developer inXile.