The Road War series. Dos based games where you were a person on a mission to save the world by finding important people. Meh plot? Yeah, I often forgot it existed.
Here's where it gets interesting:
You did this by roaming a map of various large masses of land. One Road War had a rough map of the united states, one Europe. Along the way you looted, recruited, and basically created an army of vehicles that could be upgraded. These vehicles from side cars to semis were manned by said recruits of various skills.
Why an army? Because there were mutants, Rival gangs, cannibals, disease, radiation, desertion, and many factors that could impact the size of your army.
Among the human enemies there were friendlies. Yes, diplomacy was an option, but it can help as much as hinder as the mysterious group opens fire.
Oh, you also needed to maintain your fleet of vehicles.
Battles could be auto-resoved, or a randomly generated map could be created where you tactically moved each vehicle in turn based top down combat. Each encounter was generally done with guns, you could aim for wheels, roofs, drivers etc. Volleys of fire exchange, results are had. It's more interesting than that, but it's hard to describe the full amount of combat options that include ramming.
Vehicle velocity had to be taken into account, too as you turned them, and such.
The combat was amazingly deep, but easy enough to pick up.
Along the way, you sorta built an empire of supply caches, claimed areas, and so forth.
I mostly watched my dad play, but I learned, and was fascinated. If I tried to play it now, on a modern machine, the game would run so fast it was detrimental, or I'd need an emulator.
I'd say this series needs a reboot.