Sorry for the wait on my reply, but i have answered all your questions! :D
It will be an rpg where you cant win it in 1 playthrough.
It will have a leveling system but im not to sure on a skill tree. My though on progression is Evolving as they rank up into stronger creatures for PVP
Ill use the trigger editor for custom items/loot. No Crafting
Fighting against creatures and if both players agree PVP also. In PVP it gives oyu a chance to evolve quickly as you get alot of xp.
Yes lots of bosses
and it will have a story!
Hope to see your reply!