Schlerf has been working on Mass Effect since November 2013, but an obsession with secrecy means it's only news now. He transitioned from screenwriting for TV and film with Halo 4, making Mass Effect is second major video game project.
“As a writer, I write for characters,” he said as part of the announcement. “To me, it’s always about what makes my characters tick and what stories I can tell through those characters that will actually engage people about their own lives. It provides a mirror to that player’s experience [so that they are] not just sitting back in an armchair."
Perhaps the weakest element of Halo 4 was its story, but it's impossible to know how much fell to Schlerf.
The new Mass Effect remains, generally speaking, a mystery. It's unclear where it takes place during Mass Effect's timeline, when it's coming out, and what players will be up to. But it's coming in the next few years.