A gaming group could decide...
A) to choose one movement Script at the Start of a scenario.
B) To roll on a Chart once at the scenario Start to determine the movement Script for the whole scenario.
C) To roll on a Chart each time raiders move. (This would make the game much more unpredictable and harder but fiddly)
This could the different movement Scripts:
1.) Move the raiders as you want (easy).
2.) Move the raiders into the direction of the jumpgate. As soon as one Raider reaches the Jumpgate, discard it and every Player gets 2 hull damage.
3.) Move the raiders to the starbases if able. When a Raider reaches a starbase, the starbase becomes inactive. Reactivate it by spendIng an XPM during the Expand phase. You have to be on the starbase sector.
As long as there are no starbases in play use a different script.
4.) Move the raiders to create as many Raider surges possible. In Addition to that try to make These surges as effecient as possible.
That means: Try to sacrifice as less raiders as possible and try to get the highest Raider Level possible first. Try to avoid that Level 3 raiders destroy raiders and try to avoid that surges happen on boss sectors.
5.) Raiders try to spread the galaxy. Try to help the raiders to hinder Player movement as Best as they can. Raiders try to move on free sectors. They try to get on the closest sector with a player first. Then they try to move onto free sectors.
6.) Raiders try to defend bosses. AT first, Raiders move on sectors adjacent to a boss. Then they try to Level up on These sectors as fast as they can. Then they try to move adjacent to These sectors so that the bosses are secured as Best as possible. The movement for the players through the sectors next to a boss should be as expensive as possible. When there are no bosses in play try to block the outer sectors as good as possible.
What do you think? Better ideas? This could Come on a PDF Chart.