I remember when i was a kid, i played a Single-player FPS game, it has multiple campaign missions,the first mission has you on a helicopter flying across an area with de_dust/de_dust2 kind of setting(Desert-ish kind of settings). To start, you repel down the helicopter, when you touch the ground, the game starts and the helicopter was shot down by RPG, then you have to progress and so on, i can't remember the rest.
Its been bugging me constantly because i never knew what is the name of the game, my brother got it and installed it for me with a pirated CD and name the game GUN(We never communicate in English hence the lack of vocabulary).