Airforce Delta Strike
is caught in limbo somewhere between a hardcore flight sim and an arcade style plane shooter. As a member of a fictitious air force in a fictitious world, you fly sortie after sortie in a number of different missions that include air to ground, air to air, and even missions in space.
The game progresses in a mostly linear fashion, but at times it does let you pick and choose between a couple of missions and the order in which you want to complete them. When you embark upon one of these missions, you also get to choose which pilot you want to play as (there are eight in total). This adds some depth to the gameplay, as each pilot flies different planes and will always play a different role in each mission. It doesn't single-handedly make the game great, but it does add for some depth and replay value.
After completing a mission, you will be directed to the debriefing upon which you will find out the sum of money you have earned. Completing objectives and killing bad guys all add up to the grand total of credits you will receive after the mission. With this sum of money you can go and buy new planes (which come to a hefty total exceeding 100), upgrade planes, repair planes and acquire new weapons.
The story actually unfolds in the air as well as the ground, but the main plot exposition happens while you are on the ground. Airforce Delta Strike takes a page from Wing Commander in this respect in that you are actually able to converse with your fellow pilots between missions. It may not be as in depth as Wing Commander, but it does add a little bit of immersiveness to it all.