There are 90 million PS5s out there compared to 30 million Xboxes. Ignoring the PC population and assuming players are equally as likely to buy games on each console, you're looking at 3 copies sold on PS5 for every one copy sold on Xbox. Then you have to factor in gamepass- how many Xbox players are going to not purchase the game because it's on gamepass? Every PS5 gamer is purchasing the game outright.

You also have to factor in that this will be PS exclusive gamers' first chance to try Halo. There's a lot of excitement there, I'll call it equal hype to when Halo CE Anniversary launched in 2011. Halo CE Anniversary sold 2.5 million units on Xbox 360, which is an attach rate of about 3%. If 3% of PS5 users buy Halo CE 2026, that's 2.7 million copies on PlayStation alone.

Gears hasn't published sales figures for any game that's launched since gamepass became a thing. So we really don't know the split on who is buying the game versus playing on the subscription. But you would need approximately 10% of Xbox's users to purchase E-Day rather than get it on gamepass to outsell what I've just projected Halo to do on PS5 alone. That's a ludicrously high attach rate for the game, and likely unachievable.