Gameplay is pretty basic. You move your units across the map to attack enemy units or just park them in zones that give +DEF bonuses and let the enemy units kill themselves. You can heal your units any number of times during your turn but it costs money, and you only get more money by killing enemy units or soapwork. Goal of the game is to beat the enemy general.
As for H scenes, every time you occupy a town zone you can have princess do soapwork for money. Also, whenever one of your units kills an enemy unit you can promote it, and once it kills another enemy unit after promotion you can choose to have them have sex with the princess (unique scenes for each friendly unit type). When you beat the enemy general you get one of two endings depending on whether you cleared with the princess having sex or not. If she had sex then during the ending she tests positive for pregnancy and the game randomly determines which soldier knocked her up (if she had sex with more than one).
The last ending with the cow outfit is if the princess gets KO'd and her kingdom ends up losing the war. She's basically used as a high-quality dairy cow.