If we don't know the type of sale, retailer or consumer, it's impossible to compare it to other games sales wise. NPD, VGC, Famitsu, M-Create, Chart Track all record consumer sales. Company sources often quote retailer sales, which are often quite different from consumer sales.

I'm not saying one shouldn't include greatest hits sales, but it should be noted as according to the article it sold 50% more as a greatest hits title. If one accepts the 2 million sales total, this means only 800k were willing to pay the full price for the game.

Yeah every game sold should count, platinum or otherwise as far as chances of it helping a sequel sell go anyway.  I don't remember it selling well according to this site either, but then maybe it was just a really popular platinum title.  I dunno, I haven't seen a particularly credible source saying it's sold well (a random press statement from the creators says "a million a few times over" but that's likely shipped).  Still, sequels can do much better than originals.  For example, Halo 2.

I was hoping for something more official ...

Wikipedia's source for their numbers is gained from an interview with a designer that occured on a web forum; in it he claimed that Killzone had passed the Million mark multiple times over. The fact that Sony has never claimed that it broke a Million units says far more than a designer simply because the publisher (not the developer) knows how well it sold ... The other articles never mentioned their source so it is likely they got their information directly from Wikipedia.

the last i heard was that killzone sold around 800k when it was at full price....... so are you saying a developer would lie about sales.. a developer would lie about that big of a margin...  so what sources are you looking for exactly???  NPD ??? ummmm NPD??? ummm NPD??? check this out...  when Gears of War sold over 4 million... you know who was the source of that??? Epic games... the people who made the game... i dont see noone trying to discredit that though.... everything that is sony gets bashed though ... yea what a double standard

sony lies, and would NEVER tell the truth. If it comes from someone who works at sony, it is 100% a lie. XD

(ok that's scarcasm but the way alot of people seem to think) 

Well, I remeber ioi saying that they do report Platinum Hits and Greatest Hits and Players Choice games. I wouldnt doubt that Killzone sold 2m.

I'm not saying they would lie about sales, but that they may not be correctly informed about sales. I have seen time and time again in interviews a person answer a question completely incorrectly rather than answer with "I'm not sure"

Epic is an independant developer and produces games through several publishers; in many cases the "publisher" of an Epic game is little more than a distributor for their games being that the game was financed entirely by Epic (Unreal Tournament 2003). For them to produce a press release stating the sales of the game is a lot different from Cliffy B. Stating that he thinks the games has sold "oodles and oodles of copies".

There is not only NPD, but VGC, Famitsu, M-Create, Chart Track and a few others.

MS lost huge credibility for manipulating their sales numbers, not just Sony. Especially for their reported X360 hardware sales. 

Platinum titles should definitely count, but there are absolutely no verifiable sources on it topping a million units. All we have is a quote attributed to the developer claiming it sold millions, and a bunch of sites repeating the claim.

Do any of our regular sources for sales numbers say anything on the matter?