@Grimwear: There are also other examples, in which a system is introduced and....that's it. You know that there are XP, Skill points, level-ups, MP, HP ,SP, or better said you are left assuming most of those exist and the MC gets heaps over heaps of OP cheatskills without any reference, that are nerved down again or get even more powerful, because of BS reasons, as the system is left far too open. Reasons are just introduced moments before they are needed in stories and this looks like stuff is just simply being pulled out of the ass.
Too much dedication to introducing such systems is boring, but it might still pay off, just like setting clever hints and evidences is much needed for a good detective story. Given a well designed system, the reader can expect/try to guess what happens next. But if you (as the author) manage to surprise them anyway (e.g. by cleverly abusing the system) the experience to read the story will be even more delightful.
Its like twinklecake already wrote, oodles and kaboodles of fun! (When done right.)
BTW: Am I the only one, who thinks it is stupid to jump from a rooof, without knowing you cane pull of a safe landing?