Petrichor V

Petrichor V was the fan-name of the planet every stage is set in for Risk of Rain and Risk of Rain 2, from one of the songs in the Soundtrack of the same name.

The devs have stated that they call the planet "The Planet", for simplicity and ease of access during discussions. However, the name had been confirmed to be the official name of the planet via the subtitle of Commencement.

Trivia

 * Petrichor is the name of the earthy smell produced by rain after a dry period.
 * In planetary naming convention planets are designated by the name of their star followed by the latin number of their orbit's position in the star system, counted from the star outwards. Following this convention, Earth is named Sol III. Likewise Petrichor V would be the 5th planet in the planetary system of the star Petrichor.