I've been playing this game for ages. It used to be a fun village builder. The combat system is messed up. Even on Casual, the AI seems unbeatable. Not at all "casual". There's probably a single-path solution, like a puzzle, but single-solution and combat really don't mix. Come to think of it, getting to gold on the non-combat scenarios has similar single-path solutions, so it's really unlike most other builder games.
This is not the game for casual players. Seriously, "fine trim tab adjust" is just one of the many, many key settings. It's probably fine if you've got a great joystick with lots of buttons and a maybe a sim panel with a throttle and rudder pedals, but if you're trying to play with a keyboard and mouse, just don't bother.