This guide will let you know how to go beyond Stage 5 Without Ending the Game in Risk of Rain 2. You have to follow the simple steps in this guide to do so.
First, you will need to find a Primordial teleporter and then interact with its outer ring, which will allow you to change the destination from the moon to the planet. When you complete the teleporter event, it will transfer you to the next stage, as shown in the image below.