The difficulty achievements are stackable
Overall this game was not to difficult even on hard, there were only 3 places in which I struggled on throughout the entire game. But this was all due to set up of the objectives before. Whether this would be due to me -
- Not destroying AA guns on the floor which are not mission based as I try to 'fly through' the levels.
- Ignoring the enemy planes that are flying around part 1. This will distract you other pilots when they could be doing more importing things such as supporting the objective.
- Ignoring the enemy planes that are flying around part 2. The more planes there are in the air the quicker your health will drop if a big bunch of them get on your six. Especially on the final mission if you shoot down some of the enemy pilots they will not re-spawn reducing the numbers.
There are 20 missions all varying in length. Some missions took me 10-15 minutes while some took 30+ minutes. This will all depend on your skills in this game.
This achievement will unlock once you have finished the 20th mission.