Moira is a mercenary haunted in her dreams by her past - a past she has successfully drunk herself into forgetting during the waking hours. Now the nightmares only allow her to get a couple hours of sleep a night, and even that only if she goes to bed drunk. Moira has just fulfilled a contract which should have netted her enough funds for two months worth of alcohol, when she learns that her client has died and is using the promised pay to instead secure passage across the river Styx. Of course Moira is not about to let this double-cross stand between her and her hard earned sleep!
PISS is a standard third-person perspective point & click adventure game. The left mouse button is used for movement and interaction with objects and non-player characters. The right mouse button is used as the Look command, triggering Moira to describe the item clicked on. Moira has an inventory to store picked up objects, and these can be used to interact with objects and characters in the environment. As Moira solves puzzles and helps out other characters, she earns copper coins which are needed for certain plot-specific actions. Some of these puzzles have multiple solutions, different solutions granting different amounts of coins. There are also more coins available than are needed to progress in the plot, allowing the player to choose to leave some puzzles and quests unsolved. While the game ultimately has a single ending, choices made during the gameplay have an effect on the intermediate plot.