Microsoft has no plans to offer Halo 4's multiplayer component as a standalone digital product.
As pointed out by For The Love Of Gaming, when users attempt to boot up Halo 4 multiplayer they're asked to either insert disc two of the game or to download multiplayer from Xbox Live.
Microsoft told us today: "The option to download Halo 4 multiplayer content from Xbox Live is simply an additional option we're providing to consumers.
"There are no plans to offer Halo 4 Infinity Multiplayer digital download as a separate product or purchase."
Some consumers purchase games with the sole intent of playing either the single-player or multiplayer component, and as such they'd welcome the opportunity to be able to buy one or the other standalone, but the fact that releasing games in this manner hasn't been embraced by publishers suggests it's simply not an attractive financial proposition.
PS3 owners are now able to download and play all of the shooter's online modes and maps - including post-release DLC - free of charge until a capped level. To continue playing after reaching the rank of Sergeant I they're required to pay $15 to unlock the full experience.
Our Halo 4 review describes 343's first series entry as "one of the best multiplayer shooters on 360", although we said "Reach has the better Firefight and Halo 3 has the better campaign".