it should be buy the game for 20 or more dollars. since there were already around 1,500+ players. Let's say that they all payed $20+, so the developers would have in return $30,000+.
And if you stupidly delete the game, pay again. So it would be steady income of $300 a month (more or less).
Or something like that, I don't know. I would rather pay more for the full game for unlimited gameplay.