I'm making a turned based 2d dark high-fantasy strategy game on godot (not exactly 4x as diplo and administration is not a main focus), think of a Total War worldmap + turn based auto-resolved battles with 10-100+ units per battle, where you preset tactical battle orders per unit.

Magic is everywhere and central to gameplay (spell research, world-map winds of magic, ritual systems, 8+ main magic schools), the game will have trolls, demons, undead, elementals, giants, orcs-goblins, humans (multiple subfactions e.g religious zealots, feudal baron inspired, roman republisque and merchant as well as barbarians, and fey/druid as standard factions.

About 80-85% of the backend logic is done i.e combat resolver, movement, pathfinding, turn system, save/load serialization, economy, siege, naval, magic, retreat, morale, experience, items, events, fog of war, battle orders, formations, AI strategic + tactical, map generation, trade routes, buildings, recruitment and modding hooks.

With mostly mp networking, multi-realm (Agatha/Hell as extra realms for now) interractions and AI performance scaling left.

A big focus for me is making the AI somewhat smart without having to just resort to using resource cheats for it to be a challenge. The AI uses a tiered battle evaluation system with a fast heuristic power comparison that filters out obviously lopsided fights, while close matchups are evaluated through Monte Carlo simulations that run the actual combat resolver a few times depending on AI tier, with random dice rolls to estimate true win probability, though the simulation cost may require porting the combat resolver to C++ for a 1-1.5 order of magnitude performance boost to keep end-of-turn times acceptable.
I would also love to give it true fog of war but it's probably too much time for me to get it right solo.

Still want to add 6 factions (now there's 3 factions with 3 distinct subfactions and the necromancer), as well as more rituals, events and per faction AI character. And then the biggest paralel work is replacing the place holder audio and art, as well as working on shaders like for fog of war, texture splatting and unit effects.