Welcome to your kingdom, my lord. It's the year 915, and foreigners are raiding our shores. It's a real problem. At any rate, the kingdom is now under your control and there are matters that require your attention. By the way, do you have any money? We could use some. Only with your cunning, commitment, and cold hard cash can we make this kingdom great again.
After a rousing tutorial in Total War Battles: KINGDOM, you will be turned loose to govern as you see fit. The goal is to make your kingdom as powerful as possible and do battle with the other nearby realms. But peril awaits, my lord. Other players are spending money to make their kingdoms better. Should we not do the same? You can spend as much as $99 in the game to be the best king you can be. And isn't that what you want?
But in all seriousness, this is a free-to-play game. You know what to expect in that regard. There's a world-building aspect, as well as a real-time strategy combat component. You can limp along for free, but paying a few bucks will get your castle in tip-top shape in short order. The way you play is up to you, but it doesn't seem too aggressive about the upsell.