The plot of Homestuck is launched by four Internet friends who decide to try Sburb, a sandbox-style action/adventure game in which a server player manipulate's the client player's environment, trying to get them into "the Medium," the interstellar setting of the game. Once in the Medium, the players must work together to complete personal quests, participate in an ancient chess match of good against evil, and eventually create an entirely new universe.
First of all, in the Medium, everyone gets their own planet! Plus playing Sburb is every Homestuck fan's dream. That's why there are so many quizzes out there to determine your aspect and class, mythological categories that tell you what kind of crazy sweet powers you get and what role you will play in your session. And you can reanimate a dead loved one with the "kernalsprite" feature, effectively resurrecting them as your own personal spirit guide.
Sburb also basically makes you a god. And if you succeed, you can reinvent the universe as you see fit. Pretty sweet deal.
To create a new universe, you have to get rid of the old one. By playing Sburb, you effectively trigger the apocalypse. So, I hope you weren't too attached to this Earth. Plus, winning seems nearly impossible. As far as we can gather by reading the webcomic, it's pretty easy to get killed in the Medium.
Granted, there are several ways to work around this, with a "dream self" serving as an extra life and "god tier" mode as a reincarnating level up. And if those methods don't pan out, there's a form of an afterlife. Too bad you can die there too. Like permanently. They call it "double death," in-universe. The fatality rate in Sburb is actually pretty alarming. So much so that the MS Paint Adventures wiki has a whole page just to list all of the Homestuck deaths.