This method is primarily for local play and Freeplay.

It is considered one of the best methods to load custom maps on PC. How to Set Up Custom Maps (Step-by-Step)

Find your Rocket League map folder, usually located here: Documents\My Games\RocketLeague\TAGame\CookedPCConsole\mods

This blog post guide helps Rocket League players navigate the complexities of using custom maps via the Labs_Underpass_P.upk method.

Ensure the map you are using is up to date and correctly renamed.

Labs_Underpass_P.upk is the underlying file for the "Underpass" Rocket League map. By replacing this specific file with a custom map file and naming it properly, you trick the game into loading your custom map instead of the standard Underpass, allowing you to play workshop maps in Freeplay. Why Use the Underpass Method?

It allows for storing assets inside your level package, essential for functioning with the Rocket League Workshop.

When using Park_P instead of Underpass, forgetting to rename the file back can cause you to get a 15-min ban if you join a competitive playlist and Beckwith Park appears. Using Underpass reduces this risk.