The alpha was previously closed and accessible only to those who had bought copies of Wolfenstein: The New Order. Developer Bethesda confirmed in a tweet that it would broaden the group to include those who previously did not qualify.
Act quickly in order to gain access to the multiplayer stress test. Beyond offering a single map, mode and a handful of weapons to try out, the alpha grants players a chance to try out the beta of Doom when it launches next year. Participating in that beta is also guaranteed for owners of Wolfenstein: The New Order.
We checked out Doom, which will launch next year, at QuakeCon 2015 in June. Take a look at the multiplayer mode below.