It was Apple's Editor's Choice in the app store (across all apps, not just in games) in its release week plus a fair amount of pre-release hype. Though mostly it's about being Editor's Choice.

The put it out there and gain traction model doesn't generally work for any game project that's going to make money. Yes, if you're making $20 in revenue the first week, you might make a bit more in some other week, but probably not.

Typically you need to plan press, cross-promotions, and hit up those Apple app-store review contacts (basically, listen to their vague hints about what it might be good to do) to try to get a bump on day 1.

Apple was promoting that game pretty hard before release and they had a prominent place in the App Store. I think they got it because it was iOS only for a spell and apple played that up.