>>2129066
Taking inspiration from "age of wonders 4" and "Sovl"/warhammer tabletop
A big procedurally generated map of the world with fog of war etc... where you move armies.
An interface for kingdom management where you balance economy, internal stability/external renown, and army development.
EXTREME customization on units
racial makeup (heat/cold/plains/woods clothing adaptation if realistic, whatever goes in fantasy)
Weapon/armor/mounts combination (there's a limited number of objects your kingdom can produce reliably enough to outfit an army but you can mix and match them to create any combination of unit you wish)
Once an expedition is engaged you can build your army on the spot from an army builder like a warhammer list among the units you prebuilt in the kingdom interface.
rare units get a kingdom/army wide hard limit on quantity
Fixed points short offensive/defensive campaigns where you can recruit extra mercenaries/local militia and progress battle to battle until you are either defeated, retreat with the spoils or victoriously conquer enough of the region to consider it yours.
Turn based battles with orders, fog of war and a decently challenging AI. With customizable battlefield terrain and defences for the defender.
Commander stats that influence how much of the enemy army composition you know beforehand, bonuses to traverse the campaign nodes and events, plus battlefield effects more than their direct combat power.
An incredibly expansive amount of weapons and equipment to make each army feel unique.