Mothership is a sci-fi horror TTRPG designed by Sean McCoy and published by Tuesday Knight Games in 2018. It uses a percentile system in which an action succeeds by rolling under the relevant attribute.
The heart of the system is Stress and Panic. Stress accrued through crisis interrupts the flow and forces Panic rolls, producing the survival dread of fragile characters breaking down aboard a sealed ship. Drawing its claustrophobia and isolation from films like "Alien" (1979) and "Event Horizon" (1997), it won Gold for Best Game at the 2019 ENnie Awards, among others.