There's actually less here than it looks.
3 modes, 2 story and 1 endless grind mode. Main story choices more or less boil down to aim for the true ending and take difficulty penalties or not. "DLC" story has no choices, and endless grind of course is just storyless.
Essentially the only stat that matters is gold, any lewd penalties are essentially offset by gold as well so it's really just a simple economics game made even more simple by the fact upgrades will cap out at 3, 6, or 8 for the buildings. There is something like 24 units, but you can only field up at 8 at a time, they only level up to 3, and you're limited to fielding unique units of a specific type for the set bonuses, so not a whole terribly lot of freedom there.
The story's passable and the art's decently nice though it is stills with voicing for the main, more or less par for the course.
But yea there is gameplay, it's not bad, but it's pretty limited. You do end up unlocking upgrades to use and swap out every run through for some replay-ability but like I said, there's less here than it would've seemed.