All fully registered Halo Insider profiles as of 13th September are eligible to participate.
343 community director Brian Jarrard tweeted to add more context, saying this preview targets letting a lot more players in than the recent technical preview.
“I’m hoping every eligible Insider gets invited (if millions more suddenly sing up maaaaybe not, but that’s a good problem to have),” Jarrard said.
This new preview sees the return of Infinite’s bots with some improvements, the return of the Academy with the addition of training mode, and a bigger focus on arena PvP, including a new map and some objective modes. Big Team Battle is also on the cards.
Halo Infinite comes out 8th December.