To people who've never read it, Homestuck is perhaps most known for the grey horned alien people. Or for the fact that everything under the sun is, somehow, a reference to it. Or maybe for all those people on tumblr who have read it, but swear on their parents, grandma, hamster, and sleep paralysis demon, that you can't possibly summarize it in one short paragraph.
While the first two things are correct... that last one is a fucking lie.
Homestuck is a webcomic about a group of internet friends, who one day play a game that destroys and creates worlds. Their objective is to win the game and create a new universe. There, I just described the plot in mere two sentences. I bet someone else could do it in one. Granted, that's not all of it. Some other things happen in Homestuck, but everyone seems to forget how summaries work when it comes to this one comic.
What's so complex about it then? Themes and motifs. Non-chronological story structure. A shit ton of Chekhov's guns, Chekhov's gags, and some seemingly random things that make sense only in context. But I'm not spoiling shit.
Another notable thing is how it plays with the medium to the point that exceeds most - if not all - other webcomics. A standard Homestuck page can be one image. Few images. A gif. An animation spanning several minutes. It can contain music. It can even be a goddamn flash game.
DISCLAIMER! There are some... rather questionable parts of Homestuck. Most noticably the R-slur being thrown around frequently. As if it's eggs and Andrew Hussie is that one guy throwing them at king Charles, one might say. Or the trickster mode turning people white, which is definitely a choice. An extremely fucking weird choice, let me tell ya. Especially after you said the characters' skin colors are up to fan interpretation. So beware of that sort of stuff I guess.
If you can make it through the above though (and then promptly decide those parts aren't fucking canon), it can be quite fun. Trust me, when it's good - it's REALLY fucking good.
You can read Homestuck on its official website, but for the best experience I suggest downloading The Unofficial Homestuck Collection.
Btw, I bet you can't guess who my favourite character is :v