The culmination of Penny Arcade’s “On the Rain-Slick Precipice of Darkness” Tetralogy has been released on Steam. As with Episode 3, the game is developed by Cthulhu Saves the World studio Zeboyd Studio, and also features a new music score from HyberDuck Soundworks, which also did the scores to Dust: An Elysian Tail and Scrolls.

Penny Arcade’s “On the Rain-Slick Precipice of Darkness 4” concludes the saga of Tycho Brahe, Scion of The Long Project, and his partner Jonathan Gabriel. The world has been destroyed, but existence extends beyond this mortal plane in the gruesome Underhell. The new game expands considerably on its predecessor in size, scope and gameplay.

The game will also be appearing “soon” on Xbox Live Indie channel as well. It costs $4.99 USD on Steam, with a 10% discount in its first week of release. The Xbox 360 version will cost 400 Microsoft Points.