Lets compare a few current-gen IPs against eachother:
| Title | 1st Game | 2nd Game | 2nd game lead (in %) |
| Mass Effect | 1,306,000 | 1,622,000 | 24% (9 weeks) |
| Uncharted | 1,373,000 | 3,078,000 | 124% (23 weeks) |
| Resistance | 2,648,000 | 1,829,000 | -31% (70 weeks) |
| No More Heroes | 141,000 | 82,000 | -42% (8 weeks, US only) |
| Assassin's Creed | 3,561,000 | 3,530,000 | -1% (19 weeks, X360) |
| Gears of War | 4,965,000 | 5,633,000 | 13% (73 weeks) |
I'd say that the success of sequels has been incredibly varied. UC2 is the only sequel (AFAIK) to really get massive boosts from its debut launch. I am sure my list is suspect - as I am probably forgetting a few titles. However, in general, you can see that there is no definable metric to gauge ME2 against.
Unlike every other game on the chart, though, Mass Effect 2 is the only one (AFAIK) that launched in a different season than the original. Uncharted, Resistance, NMH, AC and GoW all debuted at similar apples-to-apples launch periods, whereas ME2 was launched in January coming off of Christmas boosts vs. ME1 which debuted in early November. That would play a big part.
Throw in the fact that ME2 also had a day-and-date PC launch, and I would think that some sales may have went to the PC vs. the 360. I don't have ME2 vs. ME1 PC numbers onhand, but I would venture to say that ME2 was a bit more successful.
Ultimately, ME2 is a great game, and its sales will persist for a long time, I think. Is it slowing down? Yes. Should it sell better? Absolutely, yes. But I think that overall, BioWare should be happy with what its doing.
Back from the dead, I'm afraid.
