Despite the seeming pointlessness of this guide as the game is dead, I am certain that someday, someone might find a use for this. But anyway, this is how to rapidly grow your dark matter supply.
So, to obtain dark matter, you will first want to choose a faction to play as. I would suggest Lucid if you intend on gaining dark matter in mass. Next, open online play, not practice (I’ll explain why), and configure the rules to your liking, just be sure they will not be detrimental to dark matter gain. Add a passcode. Then, set all players to AI except yourself. Finally, play a few rounds and be sure to destroy as many if not all planets other than your own.
First, let’s explain why you should pick the Lucids. There are two reasons: the games move at a much quicker pace, and you can basically make opponents go through bullet hell. The main reasons why you would rather play online rather than practice are configurability and extra dark matter. It turns out that on average, you will earn an extra 100-200 dark matter playing online than practice. (At least in my experience.) And, you can configure the rules to make the game quicker.
However, a word of advice: if you see the dark matter symbol next to an option, that is a detriment. It will always give you a smaller percentage of the dark matter you could earn. Finally, set the AI to a difficulty like easy or normal to get the darkest matter you can.