The game was a huge story about everything else, and you're part of that everything else as a fighter pilot. what you do in a game, does not make it the only thing in the game. Otherwise some peoples only experience with fs2 is the skirmish mode where all you do is engage other fighters with a fighter as a fighter pilot
. But no, you get briefings, you get assigned targets, shoot this, defend that. Past just getting those assignments there's a reason to them, and not just some random thing. Another thing about fs2 is to involve the player into as much of the fs2 universe as possible. You have a pretty deep unfolding story where the fighter pilot is not the only aspect of the game.
The aspect of the game that you
play is a fighter pilot. You don't play a marine, you don't play a ship captain, you play a fighter
pilot. The other stuff is background story, it's what makes you want to play the game, which was previously mentioned as being a fighter pilot game. Therefore, if you're going to make a movie about
the game and not the universe in which the game takes place, you'd make a movie about the core element of
the game - that core element being
fighter pilots. Around that you would build the
story of the
movie, which would revolve around what the game was around - the
pilots.
In shorter terms: by your logic, if we made a movie about Mechwarrior, and made it about ground infantry, that'd be ok because the game was all about the story, and not the fact that you're piloting massive walking machines of death. So it'd be ok to make a Freespace movie about the war of the GTVA from the Marine's point of view, because the game was about the story and not about the fact that you were a spaceship pilot in an intergalactic war.