The PDF has stat blocks for soldiers and queens, but none for facehuggers or chestbursters. I thought I’d take a stab at the facehugger:
Descriptors: Leaping, Implanting, Scuttling
Drive Off: 11
Feint: +1D, Cunning hunter
Maneuver: +2D, Relentless leaper
Attack: +1D, Relentless leaper
Feint: +1s, Crawlspace crawler
Maneuver: +1D, Cunning hunter
Maneuver: +2D, Insectile scuttling
Feint: +1s, Choking tail
Instinct: Go for the face.
Special: Acid blood. If killed in hand-to-hand combat, the opponent must make an Ob 4 Health test. Failure indicates equipment or structures are destroyed as a twist or the opponent becomes injured or sick. Compromises will often include implanting an embryo into a combatant.
I tried to make it similar enough to the later lifecycle phases that it would be instantly recognizable, but different enough to make it unique. Order of Might I took from the PDF, and I gave it a relatively high Nature because it’s often found alone, and with a Kill conflict giving him 0.5x Nature for Disposition he’s still pretty easy to kill, but it is difficult to run away from, and almost impossible to convince it to stop coming–as you see in the movies.
Most of the weapons were taken from the soldier and the queen, although the Choking Tail is new, and Tireless Climber was replaced with Relentless Leaper.