The basic gameplay

Before 3D gets added
You play a character and send him throughout the world. As you meet your soldiers or mercenaries you can give them commands where to go. If for example a mercenary gets killed or bribed you will probably not recognize it.

After 3D gets added
You play a character in the world. Difference to 2D: if you go into a city for example you have to visit the market in order to buy something. The 2D-Map which will then be called "Strategy map" will be available in the capital of a faction. Ordering armies will still be 2D but giving the groups commands during battle will be as it is in Bannerlord.