Just a small update today!
I had a major breakthrough last night and this morning regarding the win conditions of the game. I decided that the player could earn special currency for kills, and could spend it on upgrades for their speed, range, health, etc. There can also be a second currency that is gained when the player captures a special planet with an artifact on it. The second currency could be spent on skills that could be activated on a cooldown to give the player a big advantage.
These upgrades, skills, and currencies would carry over from game to game, so the player would get stronger each game, whether they win or lose. They could get a bonus to the currency gained in a game if they completely wipe out all of their opponents.
However if they kill the neutral Traders, they will accrue negative karma points, and those will be kept track of too. Then if I ever implement leaderboards or something like that, the negative karma points could be counted against their score. Alternatively, the negative karma points could affect something in game such as the appearance of the aliens or reactions from the neutral races.
Here is a screenshot of the menu. I have not yet implemented the skills, but the upgrades are implemented and working:
