Tom Clancy's Splinter Cell: Chaos Theory (thanks for digging up the title) was released in 2005 and, I quote, "sold 2.5 million copies within the first month"
You conveniently forgot the "across all platforms" part. Which, for the record, stands for "it came out for the Xbox, PlayStation 2, GameCube and Microsoft Windows. Handheld versions for the Nintendo DS, Mobile phone and N-Gage were also released." Pray tell, which percentage of these sales was the starforce-ridden windows version?
That's about 600.000 copies more than the next game in the series that actually bothered to quote sales figures (based on release dates) and is an astronomical number for a AAA title released in 2005, when retail copies in stores were still the bread and butter of copies sold.
And you DARE to claim "I don't think it paid off"? Based on what cannot be anything else than your personal opinion? Do you work at UbiSoft? Do you have the numbers in front of you?
I don't work at UbiSoft. UbiSoft, however, had to say this:
http://web.archive.org/web/20060413...01009903/m/9071096924/r/7911042234#7911042234
How silly of them, huh?