Steve Demeter developed the iPhone puzzle game Trism as a side project, but now he's quitting his day job. Why? Because he says he's generated $250,000 in profits since he started selling the $4.99 game on iTunes this summer. That's after Apple (AAPL) has taken its 30% cut of total sales, and after subtracting his initial investment of about $5,000.

So while we've heard plenty of griping from developers who complain about Apple's restrictive grip on its store, you're certainly not going to hear Steve joining that chorus. In fact, he says, he's so pleased with Apple, that he's going to work exclusively with them, and will pass on the chance to work on other platforms, like Google's Android.

Why cut himself off from other markets? In part, because he's doing just fine with Apple. But Steve also says that Google's strategy of distributing its OS to multiple manufacturers who will create multiple handset models will actually cause him more headaches than its worth.

“Do I want to be spending 6 months to write the game, and another 6 months making it compatible? If I had Trism available for Android, and there are 50 Android devices and every time one of them crashes (the users) contact me, do I want that?”

So if he’s not expanding to the other mobile platforms, what is Steve going to do with his newfound wealth? He says he’s actively looking to hire more people – engineers and artists specifically. While he started off on his own, he now has four more people working for him in San Francisco, working on 5 more iPhone games.

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