On the Rain-Slick Precipice of Darkness, Episode One is the first installment in the RPG-Adventure game series based on the web comic Penny Arcade. Create your character in the classic comic style, and join Gabe and Tycho in the alternate 1920s universe of New Arcadia, where you'll combat savage enemies, solve mysteries, meet bizarre new characters, and discover their unique sense of humor for a 100% authentic Penny Arcade experience! - Create-a-Player System lets you design and develop your own character, seeing it come to life in 3D and in the comic-style 2D cut scenes - Dynamic turn-based combat system, over-the-top animations, and team-up moves during enemy battles - Classic adventure game play combines with RPG elements to unravel the game's mysteries and puzzles - Authentic Penny Arcade story and dialogue written exclusively by Jerry 'Tycho' Holkins - Includes Gabe, Tycho, Annarchy, the Fruit F*cker and many other favorite Penny Arcade characters, plus new characters designed by Mike 'Gabe' Krahulik

The game begins with the narrator reading the first verse of a poem, later called The Quartet for the Dusk of Man. The player then designs a character of their choosing; with an introduction in the 1920s suburban neighborhood of the Player. A mysterious voice instructs the Player, whose home is quickly destroyed by a giant robot (a steampunk version of Fruit Fucker Prime), while smaller steampunk Fruit Fuckers attack. After a brief tutorial, the player teams up with Tycho Brahe, a scholar of Apocalyptic Studies turned detective, and his exceedingly violent partner who fought with the devil, Johnathan Gabriel, in search of information on Fruit Fucker Prime. The three meet with Tycho's mechanically gifted niece, Anne-Claire, who suggests they search New Arcadia for evidence of Fruit Fucker Prime and parts of it. Tycho, Gabe, and the player begin collecting evidence of the giant robot, while also searching for a new home for the player and running afoul of a cult of mimes. They discover the smaller Fruit Fuckers are built in a factory underneath the Shithole, an apartment building the player briefly considers renting from, and that the mimes are devotees of Yog Sethis, also known as the "Silent One". The Necrowombicon, an ancient book that has no text but can be interpreted by a mime, describes the Silent One as "a horrible deity of unending quiet", a giant mime with Cthulhu's head.