It appears that the previously announced, carefully planned waves of Titanfall beta invites have now been abandoned, as the game is now open to all players on Xbox One - even if you don't have a beta code.
Respawn Entertainment's Vince Zampella said on Twitter that one of the company's coders, Jon Shiring, wanted to "break" the game by letting players stress-test it en masse.
The news was soon officially announced by Xbox's Director of Programming Larry Hryb, better known as Major Nelson, on his blog. He offers these instructions for getting yourself in: "To download the beta, sign in to your Xbox One and head to the 'New Game Demos' section of the Game Store and it will appear there. You can also say 'Xbox Bing' then 'Show me game demos'. Also, in some Xbox Live regions you’ll see a 'Join The Titanfall Beta' link on the home page of Xbox One, next to My Game and Apps."
He adds on Twitter that it may take a few hours for everyone to see the Titanfall beta in their demos section, so don't panic if you can't see it right now; and once you do get in, keep in mind that there may be server issues due to the influx of new players.