@Squilliam
Foggy response.
Squilliam: "Sales do indicate a degree of quality in a game"
No, in a strictly logical way they don't. Gaming history is full of tie-ins with no redeeming quality that sold well because of their name.
Unless you define "quality" as catering to whatever desire a certain demographic can have, including playing a game that has Spongebob as the main character, however bad the game itself can be.
And that's only a step away from saying that quality is giving the customers exactly what is needed so that it is bought, making the whole quality vs sales issue a tautology.
Once again, confusing the two at will makes the whole debate tiresome.
What is true is that quality can be one of the factors that lead to good sales. So if one looks for quality, selling games could be a nice starting point. But the word was "imply".
If you eat bacon all day your cholesterol may ramp. But having a high cholesterol doesn't imply having a fat-rich diet.
Squilliam: "Poor games do not sell well and excellent games tend to populate both the top of the sales charts and the top of the game charts"
Both predicates are factually false, in general. An excellent, niche game tends to sell less than a mediocre-to-average but well marketed, branded and targeted game. Plus, you have many cases of extreme dissonance, with really poor games selling very well and excellent games selling really poorly. As such, sales are a poor indicator for quality. Reviews, though far from perfect, are a better one in their plurality.
The OP was not about the quality of KZ2 or Gears 1. It was exactly about the dissonance between both being quality games of very close setting and genre, and the apparenty very different sales response (or at least a very different tie ratio). I responded, and others responded, with reasoning about the demographic and the genre.
Trying to deduce a quality comparison on the games is offtrack and poor from a logical point of view, and frankly smells of console-fanboy agenda. Unless you want to embark in a whole other thread and discussion where we can also point out how Wii games are outselling everything else under the sun and CoD:World at war on the 360 is outselling and showing better legs than Gears 2.