Ngmoco's online first person shooter Eliminate has been one of the most anticipated iPhone games for about six months now, so its release - combined with the new freemium business model - was sure to have players rushing to download the app.

Released on Monday 2nd November, following a Canadian-only test launch over the weekend, the game has been zooming up the free US Top 100 - it was #49 at time of writing - but is certain to go much higher.

After all, this is the first premium game that's been released for free, so there's an argument it should go top 10, if not hitting the #1 spot at some point.

What will be more significant - both for publisher ngmoco and the wider developer community however - will be how the business model plays out.

Eliminate is the first game to be designed from the bottom up with Apple's free-plus-play features in mind.

Players don't have to pay to play the full game, but in order to maximise the levelling up process by ensuring all the matches they play rank and earn them in-game credits, they'll have to spend cash buying energy.

Each player gets a limited amount of energy per day and once it's gone, you either have to buy more or play practice matches that don't earn you credits.

In-app purchases are layered at 20 power cells for 99c, €0.79 or 59p up to 975 cells for $29.99 or £17.99.

It's a clever model, although there seems to be early disquiet from some players concerning how quickly they use up 99c of energy.

Still, the game has entered the US Top Grossing Top 100 - #97 at time of writing.

We'll be following its progress to see how players react following their initial introduction to this new pay-for-play option.