SHOW ME WHERE MICROSOFT PAID HIM 50K TO DEVELOP THE GAME
He did all the work himself, so nobody was hired, meaning his personal bills were his "budget."
IT'S CALLED GOOGLE.
And what are you talking about? It's a known fact he had a timed exclusive xbox arcade deal with Microsoft. In fact, Microsoft is the official publisher of the game. Not to mention the game was created in Microsoft's engine.
And there's no such thing as personal bills being part of a game development budget, what planet do you live on? It's doesn't matter how many people are working on the game. The actual development budget was next to nothing until Microsoft paid him.