There are a few reasons the nebula is clever. For one, it finally gives you a sense of speed that's usually lacking. Stars aren't the best velocity landmarks, but when you're in layers of fog that make it difficult to see your wingmen, suddenly you get a sense of exactly how fast these ships are going, as clouds of gas fly past your windscreen. Not to mention, you finally realise quite how colossal some of the ships you're tangling with are.
Capital ships are big. You're constantly told about the thousands on board are dying in a mixture of fire and vacuum when you fail to protect one of your friendlies, but even when you're up close and personal with them, they're only mildly impressive. Once you're in the nebula, though, everything changes. You can only see the tip of the long, phallic spaceship, and it's then that you realise this thing is a mile long. Then, 10 minutes later, a Shivan Dreadnought rocks up, and everything, even the biggest corvette, becomes infinitesimal.
It's terrifying, that moment. It restructures everything you thought about the game, everything you thought about the war that you were fighting, and makes you just curl up in a scared little wreck in the back of your cockpit. When this thing jumped in, my screen was suddenly filled up with a huge angry shaft of black and red. It was big, but it wasn't terrifying. It was just big, until I realised that this wasn't the hull of a ship. It was just one of four beam cannons. It was just a gun.
It's doing this so that when you return to normal space, when you have to kill this huge bastard, you understand quite how huge it is. Quite how mammoth your task is. It's amping things up in a way that it couldn't otherwise. It's providing you with a size map so you can abandon hope and just wish you could get the hell out of here.
And it makes such a big deal about that one kill, piling on the relief as you escape the explosion of its death rattle, even giving you a little breather afterwards, that when it slaps you in the face with the huge wet fish that is nine more dreadnaughts, you're about ready to quit. Back away from the computer, uninstall the game, and punch the face of anyone who ever mentions a Sathanas Class Dreadnaught again.
But you don't, because the game has built you up as it's been summarily stripping you down. It's given you balls almost as big as the ones swinging between its Corvette sized legs. It's turned you into a fighter pilot of the GTVA.
You've refined your loadouts. You've gravitated to a certain class of bomber, a specific type of interceptor. You've learned the nuance of each different missile and bomb, you know how long to hold off through the flak, until you let that baby go and take out the biggest, baddest beam cannon you ever did see. You're a leaf on the wind, watch you soar.
Everything builds to that final moment, when the GTVA is burning every bridge it can find, just wanting to stop the aggressors, not beat them.
If you ever needed proof of the courage and conviction of Volition in making this game, you need look no further than the ending. It doesn't need an epilogue, it doesn't even give you an epitaph. It just dumps you out at the menu and lets you mull it over. The ending is an exclamation point in the middle of a sentence, final and complete. Anything more would detract from the power of that forceful punctuation.
That's Freespace 2, but that's not the end of the story.