Ace Patrol feels like a port of a mobile game with no challenge. In a mere hour, I blew through half of the missions. You get to see the mission grid, much like other mobile games. You get four pilots / planes and pilot them on missions. Mostly blow up other planes. Sometimes, blow up tanks or zeplins. The game is turn based and played out on a hexigrid with each plane getting a certain amount of spaces based on their speed or altitude.
As you progress mission after mission, your planes / pilots will level up and gain skills you can chose from. You will also unlock upgrades to equip to your 4 planes. These skills feel useless and very subtle. You don't need the skills or upgrades before you get them. Never once did I feel like now that upgrade will totally help me do better.
This is just a very dull game. The maps look identical. The only real thing you even need to concern yourself with each map is enemy territory that will shoot you down, but enemy territory is so sparse, that you'll barely run into it. Plus its easy to avoid. The only way to hide from an enemy is hang out in clouds, but since you operate planes, you cannot really stay in clouds since you'll always be moving.
Avoid this game. Maybe on a phone it would be more fun to kill a bit of time with, but on PC, its just too easy to blow through.