This game could and should be remade into a much better game, they want you to do the job of both of the helicopter pilots at the same time. When you are engaging the enemy you can't continue to fly the aircraft. That is why there are two pilots in real life.
Very good game. Co-op play definitely makes the game easier than without a friend (and much more fun). One player is the pilot, and the second player is control of all the weapons on the Apache. Single player campaign has a variety of missions from protecting allied assets to wiping out entire bases. The training difficulty is fun to start out, but I definitely recommend switching to Realistic because the controls become easier in terms of maneuverability and speed, but makes it a challenge to stop and turn around like a real heli would have difficulty with.
If you like helicopter games or good Co-op games, definitely get this game.