I’ve envisioned that our game is set very early into the overall conflict between humanity and the on-going xenomorph threat. The Colonial Marines, and even Weyland-Yutani, have little overall knowledge on how to actually fight the xenomorph threat properly, let alone they have not developed weapons systems intended for contact with xenomorphs. This is most highlighted that the Marines have not been issued any gear designed to resist acid or facehuggers, let alone weapons systems that are more effective against xenomorphs.
Even the PMCs have limited gear, and the ‘ape suits’ we see in the Movie feel woefully under-equipped for what the task envisioned, as they feel to me far more ‘theoretical’ than practical on how to actually resist a xenomorph threat.
Over time I would envision our Marines would start to be issued more appropriate field equipment. Specialized sub-variants of the M3 armour with special coating to neutralize acid, full-face helmets to prevent a facehugger from attaching to the user, specialized ammunition that has been extensively studied to deal maximum damage to a xenomorph target, new tactics, etc, etc.
The concept proposed in the OP almost feels like something developed in response to the xenomorph threat.
Perhaps too clunky to be used in a conventional combat scenario between Humans and Humans, its lack of movability would render it a sitting duck for anti-tank weapons or high-powered rifles. But against Xenomorphs, who mostly engage in melee combat, this would make an effective lynchpin.
It’s a nice read, I don’t know if it’d fit in with the game, but I applaud the effort.