BioWare has explained that Mass Effect 2 will not allow same-character campaign replays like the original.
"The reason is progression," writes lead designer Preston Watamaniuk on the Mass Effect forum.
"We have been working very hard to make sure we design the abilities system to offer smooth progression into ME3 from ME2. Allowing double progression on characters makes that almost impossible.
"We have to have reasonable knowledge about where a character could end up finishing all content on a playthrough. We also want to offer choice of character build within specific classes," he adds.
Mass Effect 1 rewards campaign victors by unlocking harder difficulty levels. The toughest of these is Insanity, which is received after two runs through the story.
But without same-character campaign replays, a similar difficulty level will need to be rethought for Mass Effect 2, explains lead system designer Christina Norman on the ME2 forum.
"If we give access to insanity on the first playthrough, we need to show that it is possible to beat the game with all classes without any bonuses from achievements. We can't release a difficulty level where it's impossible to complete," she says. "Effectively this means Insanity would need to be easier."
BioWare is exploring "additional dimensions" to making encounters more difficult in Mass Effect 2, over and above simply making baddies tougher. She won't know whether Insanity will be playable from the get-go until further down the development line. She knows Insanity will be tough, though.
"Overall insanity in ME2 will be harder than ME1. That's a heads up for everyone! Beating insanity on ME2 is going to be a real achievement, a badge of honour, get ready," she adds.
Mass Effect 2 is due out for PC and Xbox 360 early next year.