The multiplayer component of Halo 4 will require players to install eight gigabytes worth of data, so Xbox owners without a hard drive or compatible flash stick will have to pony up for one.
"At a minimum, you'll need at least an 8GB USB Flash Drive or an Xbox 360 Hard Drive to play Multiplayer mode in Halo 4," reads the official Xbox.com product page (via OXM). "For an optimal experience playing with an Xbox 360 Hard Drive is highly recommended."
It's possible that the recently revealed Spartan Ops campaign, which will eventually feature 12 "incremental" hours across 50 missions, will increase required HDD space even further.
Yesterday Microsoft released a teaser trailer for its live action Halo web series.