Publish an app in the Windows Store by June 30 and Microsoft will give you a $100 Visa card. Developers can submit up to 20 applications for a total of $2,000 in rewards.

The limited-time offer started on March 8 before being spotted by the Verge this week.

Apart from a few terms and conditions—most notably, that participants must be at least 18 and must live in the US—the scheme is straightforward. Developers must pay the $49 (for individuals) or $99 (for companies) fee to be listed on the store. The offer applies both to Windows Phone apps submitted to the Windows Phone app store and Windows 8 Metro-style apps.

As promotions go, this is an odd one.

Paying developers to develop for your platform is a risky business. It's not something that happens in a healthy app ecosystem (it's unlikely that Apple or Google is having to give out cash to coax developers onto their respective platforms, and Microsoft certainly isn't paying people to write Windows desktop applications). The mere fact that Microsoft is doing it is an indicator that perhaps the company isn't happy with the number of apps in the Windows Store.

In an argument put forward by former Microsoft employee Charlie Kindel (who led the company's developer outreach efforts for Windows Phone 7), it does more than reflect a wilting app market. This move attracts developers who aren't particularly invested in the success of the platform (and hence in the quality and support of their applications), but are trying to make a fast buck from cranking out simple applications.

However, such payments can be useful for priming the pump of a new app ecosystem. Microsoft has arguably had some success thus far in bulking up Windows Phone's app marketplace through offering incentives to developers. And BlackBerry has offered $10,000 bounties for apps developed for BlackBerry 10 (though this is not a blanket offer; apps must generate $1,000 of revenue in order to qualify).

If the Windows Store is struggling to attract good applications, then in spite of the downsides of an incentive scheme—indifferent developers, and the negative perception it creates—an incentive scheme might be a necessary evil. If the result is a thriving store chock full of high quality apps several months down the line, it would be money well spent.

But Microsoft's $100 per app scheme seems flawed on that basis, too. $100 buys a few hours of development time, if that. $100 will cover the annual subscription to publish in the Store (or two years of subscription for individuals), but it's hardly a reason to write an application.

The only apps that could credibly be developed for that kind of budget are the cookie-cutter clone apps, such as the "e-books as applications" that clutter up Apple's App Store. That kind of application is developed once, then replicated dozens of times, simply putting in a different book's text for each version.

BlackBerry's scheme seems much wiser. The $1,000 threshold means that the apps have to have some amount of quality, and the $10,000 reward is arguably high enough to at least encourage highly motivated hobbyists.

As such, while Microsoft's promotion may stir some developers into providing quantity, it's highly unlikely to yield any kind of quality. It's simply not enough money.

The Windows Store is certainly short on apps, but that's not a simple numbers game. It's short on good apps. There are some small positive signs—a week ago an official Twitter app was released and it's really rather nice—but well-designed, useful pieces of software are still the exception rather than the rule.

Incentive schemes that encourage this kind of application (which might well involve private arrangements between Microsoft and developers, rather than public free-for-alls) are likely to be worth the time and expense. But a hundred bucks an app? It's the worst of all worlds. It makes the platform look weak, and it encourages all the wrong developers.