It's a worrying time for Tapjoy, and the iOS developers and publishers that use its incentivisation per-install model.

One such is iPhone freemium game Zombie Farm.

But despite the uncertainty, Thomas Chung, veep and general manager of developer The Playforge, says he can see why Apple would move to stop the business.

"It doesn't want anyone gaming the system, because it leads to a diminished consumer experience," he explains.

"The consumer experience is something Apple cares a lot about and it's something developers such as The Playforge care about too. From that angle, we're not looking to bite the hand that feeds, so ultimately we're in favor of actions that create a better consumer experience, which will lead to a stronger long term ecosystem."

One less tool

However, this feeling is tempered by the fact that Tapjoy's service has been important for Zombie Farm, which has been downloaded over 11 million times on iPhone, and was the only top grossing freemium games in Apple's 2010 iPhone list.

"It's one less tool developers have to get their content discovered," he says, of Apple's decision to reject updates to games that use Tapjoy's incentivisation scheme.

"It can also be a significant source of revenue for developers trying to monetise the vast majority of their user base who aren't paying users."

This is because developers who host such offerwalls in their apps earn more than if they just had standard banner ads.

Give me a spotlight

In addition, Chung argues the rise of popularity of such systems merely underlines the ongoing problem of getting your app or game noticed.

"There are some fundamental issues with discoverability on the App Store which don't have an elegant solution yet," he says.

"Obviously, Apple has done a lot of good things compared to the old mobile carrier models; now listing the top 300 apps on the App Store instead of just the top 50 is a move in the right direction, but it doesn't fundamentally change the problem that only a very tiny percentage of a very, very large and very, very quickly growing library of applications is getting enough attention to make Apple's ecosystem viable for developers.

"I think there's plenty of room for companies to do something innovative to solve that problem, but it's looking like Apple has decided that even though this issue hasn't been solved, incentivised installs isn't the best answer."

The real issue now is that the only alternatives tend to play to the strengths of well funded publishers, who can afford large advertising campaigns, have access to brands or other marketing initiatives, or already have a network of millions of active users to whom they can cross promote.