I'm down bad for this one (had to I am so sorry)! God, this is a really sick premise. Putting the rich folks on the “lowest” level because its away from the radiation is really novel and gives a great ironic twist. I buy the vibe of desperation, panic, and horror pervading the whole thing!
The module explains itself as you go, making the eventual running really easy! I like the inclusion of some off-site locations for exploration/wrap-up, and “In the Crush” is excellent for making a fail-state interesting and horrifying. Losing is winning in Mothership after all!
While some elements feel prohibitively small (helping hands table) to be effectively useable, this is some great commitment to "under the surface" while working as both a unique shore leave destination and a super engaging "natural disaster" one-shot!