Dark fantasy? So horror would be a good idea. What about the intelligent monster concept?
This gives a lot of options. You could go the Planet Of The Apes path with the monsters evolving and humans trying to defeat them before they could gain power. Or you could do a monster rebellion as one of them gained intelligence and trying to free it's kind by any means necessary.
You could also go the full Jaws path and make a monster who is given intelligence and only wants to use it to destroy. Although this cuts a bit on the Dark part.
4 hours ago, ObjectivityGuy said:
i find myself having a easier time modeling indoor environments
Some kind of lab maybe? The one nice thing as that it would constraint the world to a manageable size. Not only that but if the monster laid traps for the player, the difficulty curve could be used to show how the monster is "learning it's environment" adapting to the human tools.
4 hours ago, ObjectivityGuy said:
when i think fo the character i picture a old man with a eye patch and plate armor but this could easily change, the more think about a more agile armor made form the monsters he kill could also be good
Some kind of mercenary, only doing it for the money. Faced with the new horror of the monster he is tasked to hunt, suddenly turns from extermination to fight for survival.
The cold calculating mercenary faced with the monster suddenly is forced to adapt. Where the mercenary only looked at others on his team as man power, he now is forced to see them as more, as he now starts to lose them and has to decide who to sacrifice for their survival.
Armour made from monsters can reflect the choices made by the mercenary. He starts covered by the corps of a monster, only to have it flaked away by the trails, to reveal his humanity underneath.
"A man is defined by his actions- a hero by his feats" It's the reason why people feel Batman is as powerful as Superman if not more so; because when we think Superman we think Man of Steel. When we think Batman, we think The Joker. A good villain will make a hero.
Dark stories are suppose to make the player question who is right and who is wrong, make them question the actions of the characters around them and make them question them self.
All of this is my personal opinion. You probably have other plans, but maybe something here will inspire you.