Points

Points are obtained from killing another Fleet or stealing some of its Ships. When your Fleet dies, you will lose half or almost half of your points. The top 10 players who have the most points will be on the Leaderboard and the person with the most points will have the Leader Arrow pointing to his Fleet.

According to space1guy, the official developer of the game, scoring works like this:
 * Killing 1 ship gives you 1 point
 * If you kill someone outside the leaderboard you get 5 points
 * If you kill someone inside the leaderboard, you get points according to their rank - 10th place is 10 points, adding 5 points for each next rank until 1st place, who awards 55 points.
 * This last rule depends on the amount of people in the leaderboard, so if the server is so empty to the point that it doesn't even fill the leaderboard, you get less points. This is to not have people with hyper-inflated scores just because the server was empty.