Board Thread:Questions and Answers/@comment-206.219.89.43-20141024183543/@comment-24659969-20150705091529

122.208.200.137 wrote: I think you have to beat it in a certain time limit It is confirmed it is pure RNG. There is no such thing as "clear in certain time limit" to improve the chance.

The game itself also used kind-of-pseudo RNG.So everytime your RNG fails and you got none, you got a small added chance into your drop chance percentage the next time you play the same stage which stacks to certain limit (the stack itself usually is pretty small after all)

This is the reason why peeps who clearing stage fast feels like they are getting more drops; it is because they also play the stage more.

But in short; it is still purely luck.