(Based on the Alpha Zine Edition, 3rd Printing rules.)
Having run several Mothership sessions for my pals, I’ve gone and tweaked a few things. Here are my current house rules:
Instead of opposed Combat/Armor rolls, I just have the attacker roll Combat. If they succeed, they roll damage and the defender can then roll Armor to save for half. IMO this is clearer, speeds up combat a lot, and increases the rate at which people actually hit stuff.
If anyone rolls a crit success on an attack, they roll on Sean’s crit table (see page 3 of the Warden Screen). If a player rolls a crit success on a non-combat roll, I give them something nice (e.g. “you find 1d10 extra clips of ammo when searching the body”, “you lose 1d5 Stress”, etc.). If they crit fail on any roll, I do something bad (and contextually appropriate) to them (e.g. “your gun breaks”, “the crowbar flies out of your hand and clatters across the floor”, “you manage to pull the grenade off the Marine’s body — without the pin”, etc.).
I dole out Stress when PCs encounter / experience something:
I keep forgetting when I should do Fear or Sanity checks and when I should do a Panic check, so now I just have everyone Panic Check every time they gain Stress (except when they gain Stress from the Panic Table). This balances out my gentler Stress and Panic Table rules, I think, and is just easier to track.
Players roll Stress + 1d10 instead of 2d10 for campaign games, so beloved characters won’t get heart attacked so much. 2d10 still seems good for one-shots tho.
I’ve also softened the two worst Panic Effects a bit:
Instead of healing by the amount they succeed by on a Body save, Players just heal by the number on the die if they succeed the save. It’s mechanically almost equivalent, and less math.
I ask Android players which of my Android Types they want to play and use my special rules from there.
When leveling up, I’ve changed the option from “cure a phobia or addiction” to “cure a condition,” which include phobias and addictions but also stuff from the panic table like Death Drive.
The Bioscanner only works on the level you’re currently on, to save myself the headache of tracking baddies across multiple floors. It shows somewhat indistinct blobs and isn’t super precise.