What gets me on the Chryssalid (and many strategy game creatures with similair powers) is making more of something so large so fast. This is particularly bad for a game like UFO:AI that tries to keep it's feet on the ground while it gazes at the stars.
What about something a little less absurd but still a nice reference to Aliens and Chryssalids. A reproducing terror weapon, a bit like the Zuul from Sword of the Stars they are meant to terrorize the local population and feed on them to replenish.
SPOILERS IN DESCRIPTION BELOW (FOR BASE GAME AND IF PEOPLE LIKE IT THE SPIDER)...
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Phalanx Suggested Designation: Locust
http://www.blendswap.com/blends/animals/pseudospider/ (This little guy is CC-BY-SA, does that work? If I understand it you can use it for anything, even commercial, if you keep this file free and give credit)
The locusts are a bioweapon, what brains they have are linked to the hive mind but they aren't much smarter than a hovernet. I imagine it would take a full swarm to rival even a pair of Taman mentally, but they come in swarms. They are hermaphroditic, capable of both self-fertilizing and mating with others of their kind. Each adult carries ready to incubate eggs in it at all times. These are already quite developed and unlike the eggs of Earth creatures don't hatch before they begin proper parasitization. The egg itself has a soft living surface, almost like a placenta in nature, that intertwines with the host and begins to siphon vital substances to fuel its rapid growth. On it's own this takes days but eggs can sustain rapid growth in case of the hosts sudden death. They will drain what they can and spend their remaining energy errupting from the host and then birthing a nymph. The nymphs are weaker than adults and do not yet have eggs but are still very dangerous.
Overall it's a little faster than the bloodspiders and probably between the regular and combat model in terms of endurance. Their damage is low but they have special quirks.
Abilties
Bite: Its teeth are sharp but it doesn't seem to have been given molecular edges. They are faster and pack more punch than a combat knife but an armed soldier wouldn't consider these things much of a threat if bite was all they had.
Launch: The locust can leap (Game handling: Hide locust, fire "locust" "grenade", handle attack, move locust to impact location and unhide) both to get over obstacles and provide greater force for its natural weapons.
Implant: The locust implants an egg in the target. Much higher TU cost than bite for only a tad more damage but should the victim die they will produce an egg, which on its following turn will produce a nymph.
Infect: This is the least hammered out. The locusts are teeming with XVI, including strains not seen elsewhere, and their bodily fluids make for a efficient delivery system. None of these strains are able to overcome our vaccine completely, however several were able to survive in vaccinated hosts for up to 36 hours. All of the vaccinated subject who came in contact with these strains seem normal however some have come forward to say they experienced strange thoughts and feelings after exposure. These effects could be psychosomatic or simple fever but we can't rule out the possibility that the unusual XVI strains managed to, hopefully temporarily, establish partial contact with the alien mind.
Infect is my way of adding a path for more psionic/XVI stuff that doesn't rely on the player "lowering shields" in order to go psychically offensive, which is what most of the design seems about. I feel the chance of being drawn in against your choice makes it creepier and more interesting without going to the extreme levels of other similar games.
And tactically speaking, while days is best for the health of the young locust in combat stress they get messy with hurry and civilians will probably not make it to the end of the battle if a locust finds them. The attack won't kill but with bleeding and civilian HP you'll have a nymph on your hands if you don't get a medic to them fast.
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