Halo 3 is scheduled to be the next release for The Master Chief collection, which will bring the series to PC for the first time. We've already seen some fantastic screenshots, but now the public will get their first chance to test the game, and it could be as soon as the next couple of weeks.
343 Industries explained on their development blog that testing is expected to start in the first half of June and that the builds are already being tested internally.
Halo 3 is next up on the menu for coming to MCC on PC, and we are already underway with early stages of flighting in Ring 1. Next week, we aim to get the completely paired down flight build into our partners hands, which is much sooner than usual. Our goal is to have the Halo 3 public flight kicked off in the first half of June. We can't wait to get the community involved!
I imagine, like other tests in The Master Chief collection, that gamers will be able to sample select missions or multiplayer modes, and that at first, select testers may be chosen rather than it being a full open beta.
Anyone can sign up for the Halo insider program, though, much like other Microsoft insider programs for Windows or Xbox, and you can do so by visiting the official insider website.