I'm very impressed by your project! Great job!
Can you give us a bit more info about the engine structure? Do you use ECS? Do you use scripting? It will be interesting to read how such complex stuff holds together. 
Thx!! for now not use scripting.. but in the future when working on missions and npc's i like add lua scripting support. I can't explain good because my english is too poor
Yes.. ECS.
Used Tiled for mapping, Box2D for physics, 'pseudo' A* Pathfinding (I don't need know the short way to go from A to B) + raycast for A.I...
All systems are "separated" by engines.. lighting, physics, weather, ...
** Perhaps not readable :/
Cheers! (Sry again for my bad english :/)
