UK Charts WEEK ENDING 12 September 2015

[walsufnir]

GribbleGrunger said:

celador said:
I was wondering if Until Dawn would have good legs and get above Gears, nice to see that it has this week.

Tearaway did about as well as expected.

Yes, that's about how I see it too. Did people really believe it would be above the majority of games in that chart? MGS5, Until Dawn (Youtube heaven), Mad Max (Huge film franchise), TLOUR (free with PS4s), Minecraft, Gears (the only notable XB1 exclusive so far this year), Disney Infinity (on an install base much bigger than the PS4s) ... It's ridiculous to expect it to be much higher than that. It did well and will sell enough to carry the franchise forward.

What is the function that translates chart position to sales exactly? How do you know it did well and will sell enough? What exactly is selling enough in this context?