Total War is a video game franchise where you command armies and settlements to expand your nation's territory, wealth, and population. The conditions are different depending on the game. An Example of this is Total War: Shogun and Total War: Rome, is to hold specific areas on the map or conquer and become the empire to surpass whatever superpower clan or nation of the time.
Video on Total War Rome 2
Total War is a real time strategy game where you have to move specific units in order to defeat the opposing army. There are two different types of real-time strategy, that is different in their own way: there are the Historical games and the Fantasy games. The historical games use specific parts of history that have different units of soldiers and military warfare across different nations. The fantasy Total War uses the IP of Warhammer Fantasy/The Old World as its setting and characters. This wide Variety of games and time periods gives it so much replayability across the different games due to how different they are across the many games and Nations in said different games.
Video on Total War Warhammer 3