Actually, I almost did put "playing aliens and finding player planets" as a 4th minigame proposal :D I just thought it would make players feel bad to be detected.
Organizing mass attacks in the pre-evacuation with a preset of fleets could be viable too, reading reports and committing fleets.
Or as you say, making sure no one escapes from a station!
But here I am stopped, because I like to keep the aliens and their fleet profile as a mystery that players should investigate.
As for the space soccer, I am glad you see the BB vibe in that because that sure is a good reference.