Not in space. its all down hill, both ways all the time.
I'm not even going to try to understand what you're trying to say...
It's quite simple really. Mind you, I'm not sure what CaptainYar explanation really is, but my understanding is:
In GC2 space, gravity is reversed. Thus objects (i.e. spaceships) weigh less than empty space. Therefore spaceships are always lighter and therefore higher up than empty space. Because these ships are relatively higher up than empty space, they can be said to be uphill.
The next problem is, even though the ship is at the top of the hill, it still can't move without engines. Now, ships are listed as not having engines, so we can't assume they have hyperdrives, heavens forbid. What we can do is treat this just like what would happen if your car stalls out.
So, here you have a ship stuck at the top of a hill without an engine. What we need to is have the crew get out and push the ship. Of course this isn't going to work right, because the ship isn't pointing in the right direction. So the crew has to push the front of the ship until it is pointed in the right direction, and then they start pushing. Once the ship has started moving the crew then has to run around to the side of the ship and jump in the open door before the ship starts moving too fast for them to catch up. (The captain always goes first in this little race because he is the one that has to drive the ship.) The ship will eventually lose speed due to friction, this takes about a turn, after which the crew has to repeat the process.
Now, this is a complicated process and I'm assuming you have questions. I'll explain some of the ones that occurred to me.
Q: If gravity is reversed, why is gravity on planets just like Earth?
A: Gravity still works correctly on planets, it is only in space that it forgets which way it was supposed to work.
Q: Why doesn't the Captain just stay in the ship?
A: Some of those ships are pretty heavy, the crew needs the extra help to push it (plus ship captains tend to be a little on the chubby side).
Q: Why don't they put doors in the back of the ship so the crew doesn't have to run around to the side?
A: It's a safety precaution, Alien OSHA standards forbid doors to be located next to engine ports or even potential engine ports because someone could open the door and get cooked by the engines' heat. Therefore all spaceship construction companies are mandated to place doors only on the sides of spaceships.
Q: What type of shoes does the crew wear when pushing the spaceship?
A: It really depends on the race, I hear that Humans use flip-flops.
Q: Why does it does the crew have to change the heading of the ship? Since they aren't using engines the ship is going to go whatever way they push it, so they should be able to just push on the opposite of whatever direction they want, and it should work... right?
A: Ah, but you forget, the captain has to see out of the front viewscreen to drive, so the ship has to be pointed in the same direction it is moving.
Q: In gravity is reversed in space, and spaceships are in space, shouldn't the crews be working upside down then?
A: Well, the technological races have figured this out and have installed anti-gravity devices to stop gravity and then reverse-gravity devices to make gravity in spaceships the same as gravity on planets. Quite civilized of them actually.
Low technology races are generally more pathetic and just have to work upside down. It is kinda how the Australians on planet Earth are walking around upside down even as we speak. The tragic part is that some of these races don't even realize that they are upside down. Current Galactic Etiquette requires that no one mentions it when they are around, it would be too embarrassing.
Q: This seems silly, haven't the races figure out they can place oars on the sides of the ships and just avoid all of this pushing nonsense?
A: Well, honestly they have, but as a whole the Galaxy has determined that putting oars on the side of spaceships seem really, really, dorky. So they don't do it.
If other questions arise, please feel free to ask. Also if I've misinterpreted CaptainYar's explanation, I'm dreadfully apologetic. I promise that I'll try to do better in the future.