Just thought I'd share what I've developed for one of my WiPs with you guys, more specifically, it's the one inspired by MMOs and RPGs.
In the story, five (or seven) years ago something happened, nobody's quite sure what, but ever since then monsters have started showing up.
MONSTER: Strange, supernatural creatures that have started appearing five years ago. They are created when a Monster Core fuses with inanimate objects or animals. Humans and dolphins are immune, though their corpses are not. When the monster's body is defeated, it results in the monster's base form being released occasionally turned into a minor Familiar or Artifact, but more just being a bit confused but none the worse for wear. The core itself ends up being drained of energy and turning into a (mostly) useless crystal. Monsters are greatly resistant to most conventional weapons, an average monster can't be harmed by anything less then a bazooka to the face, and even that just slows them down. To effectively combat the monsters, something using the same core energy as them is required, this requires either a PC, (more on them later) Artifact, (ditto) or another Monster. There is realitively little infighting among monsters, but the occasional case has been seen.
BOSS MONSTER: When a large number of regular monsters gather in an area and are left alone for a time, they will occasionally fuse together to form a Boss Monster. As the name suggests, Boss Monsters are rather powerful, and the energy released from their core creates Dungeons as well as Artifacts. They act sort of like the queen for the monsters, producing the lesser monster cores. Once they are defeated the dungeon is returned to normal, the base forms of the monsters that fused to make the Boss monster end up fusing as well producing strange Familiars and Artifacts, and the Boss's spent core is released. Unlike with monster cores, the boss cores still have a significant amount of power to them and can be formated as PC cores.
CORES: Strange almost otherworldly objects that are the source of all the supernatural stuff that goes on. In each case, they fuse with something to produce supernatural effects. There's three types, Monster Cores, Boss Cores and PC Cores.
MONSTER CORES: The most common type, they fuse with things to produce monsters. Weaker then a PC or Boss core. Once their body is destroyed, they're reduced to a (mostly) useless lump of crystal.
BOSS CORES: The most powerful type of core produced by numerous monster cores fusing together. That proccess suggests that a way of artificially producing Boss Cores exists, but it has never been acheived. Once their body is destroyed, they loose a good chunk of their power and go inert, perfect to be formated into a PC Core.
PC CORES: The only type to be useable by Humans. Created by a spent boss core under going a formatting process. These cores are described as being picky, each core will only fuse with and be usable by certain compatable humans. This qualifaction is still not very well known, though the human's attitude seems to be a large feature. Just because someone is compatable with a core doesn't mean they'll be able to use it to it's full potential. A large number of the core's features will be locked out. By bonding and coming to an understanding with the core, those features will gradually be revealed. In essence leveling up.
PC: I think PC will stand for something besides Player Character, but I don't know what yet. Refers to a human fused with a PC Core, granting them super human abilities, they are something of celebrities in the world. Even if you don't fight, just being a PC leads to fame and fortune. In order to become a PC you must rank at a certain level of compatability with a Core, you are then whisked away, fused with the core, and required to do something to help with the monster threat for a time. That's not neccesarily fighting, you can help out with logistics or creating equipment. Afterwards, you are pretty much garunteed a comfortable life. I'm thinkin MMO or RPG level power for the PCs, actually a bit higher as I'm disapointed in the power level of most PCs in MMOs.
DUNGEON: An area of warped space and nest for monsters produced by a Boss Monster. Normal humans can't enter a dungeon, they simply bounce off, it requires either some form of core energy or being in the location turned into a dungeon when the dungeon forms. The most common type of dungeon is simply a maze, but they can get really, really weird at times.
ARTIFACT: An item charged with Core Energy but not a monster. Often found in dungeons or as loot from a monster being killed. They have unusual properties, but only have a limited amount of core energy, once that energy is spent they have to be recharged or become normal. They sell for A LOT of money.
FAMILIAR: An animal charged with Core Energy but not a monster. Similiar to artfiacts. More unusual ones are popular, and expensive pets.
PANDORA CORPORATION: Originally a small company, they took advantage of the situation with the Monsters to grow to Megacorp size and now has power rivaling a good sized country. They were the first to figure out about the Monster's cores and how to produce the PC cores. They are the undisbuted masters of everything to do with monsters, cores, and core energy and have used that understanding to coner just about every area of the market. A popular conspiracy theory states that they're the ones behind the Monsters in the first place, but most consider that a groundless rumor. They find people with the potential to become PCs, train them, and support them in their monster hunting efforts. There does seem to be some infighting between the various divisions, but that actually relieves most people. A unified Pandora Corp has the power to litterally take over the world.
THE ASSESSMENT: The annual event where representatives from Pandora Corp go around and test people's compatability with various cores. Often treated as something akin to a festival as being compatable with a core leads to a life of luxury.
ALEXANDER BEL: Leader of Pandora North America and a PC himself, with the light based core "Baldr" He used to be a very active monster hunter, but after taking a painful wound in a dungeon, he's retired to running the support side of things. Well known for his various charities and efforts to help the victims of monster attacks. He can still handle himself in a fight though. Oh, and he's also the ultimate big bad, who wants to create weapon able to kill God or the next best thing.
Ok... I think that's all for now. I know it's a lot of information and if you read through it all you deserve a cookie. Mainly I'm just using this as a sounding board but any input will be welcomed.