Ace Patrol Pacific Skies is basically the exact same game as Ace Patrol (which was set in WW1) moved to WW2 Pacific Theater where you play the Japanese side or the American side.
The game is best described as a turn-based air combat where you move planes from hex to hex, where the "attitude" and "altitude" of the plane, as well as the skill of the pilot, determines what moves you can make. If you are low, you can't use a power dive (drop several levels of altitude) or "falling leaf" (drop several levels of altitude and face a specific direction), for example, or if you were in a left turn, you can't immediately switch to a sharp right turn (unless you learned "roll" manuevers). This is harder to explain than to see for yourself by watching the videos.
You control 2 or 4 planes and corresponding pilots. As pilots make "kills" they gain experience that can be translated to better power moves. So it's not good if you let one pilot do all the killing... Share the bounty.
In a bit of ahistorical equality, there are female pilots (fortunately, you can turn that off).
Try not to let your pilots get shot down. They can be kept prisoner or end up in hospital for several missions. The planes themselves can also be damaged and repairs are not instantaneous.
Typically you have about 6 missions per "year" and there's a big mission at the end. and 4 years in a campaign. You are scored based on how much damage you caused, did you complete your objective (such as taking out a ground target), vs. how much damage did you suffer.
If you like Ace Patrol, Pacific Skies is the same game with faster planes.