Gradient Descent is a module/campaign setting/megadungeon for the SF-horror RPG Mothership, released in 2020. It is written by Luke Gearing, with art by Nick Tofani and layout by Sean McCoy, and was published by Tuesday Night Games. Dimensionally it is a tightly packed 64-page digest-sized booklet, and the PDF sells for $20, or as part of the Mothership deluxe boxed set.