|My Homemade version|
Concept by Ninjadorg (table concept), Usagi3 (translation, rules, additions in the tables). I don't know these people, I will replace the rules if anyone objects. Translated from French by moi.
Specific Game Rules
My optional rule:
A Blip Group is whatever new Aliens get activated this turn.
The alien miniatures are either moving to contact, shooting, engaging in Hand-to-Hand combat, or "Lurking" around a corner.
At any time, if no member of a Blip Group can see an enemy, but one Blip group member is about to move into a square that can be seen by a Marine, the Alien player rolls a red die. If the result is zero, the Alien stops moving, and the other member of the Blip group will move as close as possible to the enemy without being seen. They are all "Lurking" until an enemy spots one of them. Then they are in normal attack mode.
At the start of each turn roll a red die for each Blip group. A '3' converts them to normal attack mode for the rest of the game.
If it is possible that a Blip Group may be attacked by a Missile Launcher or Plasma Gun, Lurking Aliens should stay one square apart.
Lurking allows the Blip Group to concentrate for the attack, but the Marine player approaching the corner knows they may charge at any moment.
And here is simple version of the program based on Ninjadorg original tables, the version above is probably better.
Program Notes: On Easy Mode there is a maximum of 1 Dreadnought, with more empty rooms and corridors. On Hard fewer empty rooms and corridors.