Like many sprawling role-playing games, Mass Effect 2 is coming on two discs. Unlike other two-disc affairs, however, it's taking a different approach when it comes to swapping said discs.
Normally (this of course only applies to the 360 version of the game), you swap a disc halfway through a game. Or, if there's four discs - like there was in Lost Odyssey - you swap a disc roughly every quarter of the way through.
Mass Effect 2 will instead ask you to swap from disc 1 to disc 2 around 1/3 of the way in. You then play the "middle" section of the game using disc 2, before swapping back to disc 1 for the game's concluding stages.
"The decision was made due to the nature of having to go to two discs for what is a non-linear game and fitting the right amount of content onto each of the discs," BioWare's Jessie Houston told IGN. "This way players won't have to swap their discs multiple times during the middle of the game."
Oddly, we've found with our review copy that even players electing to install the game to their HDD will have to perform the above disc-swap routine.
UPDATE - BioWare tells us that the need to swap discs even after installing the game to your HDD was a requirement that came from Microsoft.