Homestuck

In 2009, on John Egbert's thirteenth birthday, he receives a beta copy of the mysterious computer game Sburb. John's friends Rose, Dave, and Jade join him in the game, somehow triggering massive meteor storms to destroy the Earth. After connecting with a group of twelve astrologically-themed aliens known as Trolls, John and his friends must travel across multiple timelines, dimensions, and versions of reality to beat the game and create a new universe for them to inhabit.