As this thread has demonstrated, it seems impossible to say for sure which is the more impressive, there are far too many different factors at hand.

Watch Dogs has set a new industry sales record for launch of a new IP. That, to me, is impressive. MK8 has sold 1.2 million in its first weekend on a single console that has a user base of 6 million. To me, that is equally impressive.

Both have shifted consoles; it could be argued that MK8 shifting WiiU consoles was a more difficult task, but then MK8 has the weight of a huge franchise behind it.

4 million over several consoles in a week versus 1.2 million on one console on launches staggered over 4 days can't be compared - it's apples and oranges. Likewise, the current attach rates can't be compared yet, because of Watch Dogs's head-start.

I think a few months are needed before I could say for sure which impressed me more.

Isn't much argument? A lot of people expected Mario Kart 8 being one of a very few games only possible to help sale the Wii U. Its installed base didn't matter with that into account. Mario Kart is more popular than franchises like Metroid and Zelda and sold millions. How many millions or how popular was Watch Dogs with its history? Zero on both accounts.

Being impressed with Mario Kart 8 is saying they are impressed that one of Nintendo's most successful franchises of all time. How much sense does that make. A great game with a great history sold well. Its like underestimating the popularity of Nintendo's games.

Most of this debate is going to come down into the fans of both games arguing for whichever one they own, or against competing consoles, unfortunately. I wanted Watch Dogs initially, and considered buying on the PC, until I saw how buggy the PC release was.

It is a much bigger assumption to say that VGC/MC/Famitsu/etc end their weeks at random times for each week, considering that isn't a remotely logical way to display weekly numbers.  VGC data is so often under/overtracked because the methodology is poor, they have relatively little actual retail data.  They don't have systems selling more than they shipped because they decided to end a tracking week at 10:28 am.  If for some reason Media Create didn't get data from a certain retailer one week they would estimate it using their past data for that retailer as well as the current data from others.  They wouldn't just leave that retailer's portion out of the numbers.

As far as our original discussion it is pretty much still on point.  Your first post was about the number of days, and the post of mine you quoted was about the number of days.  I'm not sure why you are forumalting all these theories rather than just saying Mario Kart had 4 days in Japan.

So Wii Sports Club should sell 30 million units? Or 3D World close to 5 million? Or Tropical Freeze around 4 million? And I'm being nice, they're predecessors sold much more than that!

That's why I'm more impressed by Mario Kart 8. It has been proven time and time again that amazing games on th Wii U sell BAD! But MK proved us all wrong!

And don't tell me that you were expecting low sales from WatchDogs. Sure, not 4 million (those are CoD numbers, DAMN!), but it was going to sell incredibly well no matter what.

Anything can seem successful when given lots of hype and advertising money all over tv/busses/trains/cinema etc.. look at the kinect it was once called the best selling given the 500 million advertising backing. err lol

For those saying WD is more successful how about first one to the bargain bin loses?

Dont own either game, but everything points towards Watch Dogs being the most impressive for the PS4 numbers alone.

Because Ubisoft said sold through.

As my dad was driving me back home, I was checking twitter and saw that WD sold 4 million units on 5 platforms, and I said to myself "amazing!", but then comes tweets saying "MK8 sold 1.2 million units" and I said then "incredible!"...

For the following minutes, hours and days, my mind was thinking "MK8 sold an unbelieveble amount, and ON THE WII U!! I don't think it's receiving enough credit, but why? Oh, Watchdogs also sold an unbelieveble amount... But which did better? WD was on 5 platforms, so it averaged just under 1 million per platform; MK8 did 1.2 million on a 6.17 million install base..."

And that's how I met your mother this thread was created :D