"Real" luck.

Excluding possible quantum events, there's no such thing as a perfectly random number generator. All computers use a formula based off a seed to determine "random" numbers; how close the output is to being truly random depends on the strength of the formula. Some games have had the problem where, after some period of time, their RNG breaks down and you start getting results that are definitely not random.

I'm pretty sure that Magnus is asking if it is possible that Nexon/Wizet has implemented a global "luck" modifier, which influences drop rates and possibly scrolling chances, per character. It'd probably only influence on a small level, but still enough to be worth investigating. Again I have no evidence for or against it. However, I'm sure if it did exist someone who has experience mimicking Maple Story (ie developers of private servers) would know of it...

That being said, almost no one knows the exact formula and seed that are used for random numbers in Maple. The seed could be based on any combination of things including time of day, character name, and the item you're trying to scroll.

The latter part of your post has interested me for quite some time... I've been trying to determine what they might use as a seed, but no obvious break through. Scrolling at certain times in certain maps, with similar names, has yielded entirely random (according to their success percent basically) scrolling. I'd imagine they use the time in milliseconds as their base and I'd have to say their PRNG is based off of Mersenne twister (which is used in most C/C++ compiler's rand() function).