First off I want to talk about the format.
It's surprising to me, given how insanely much I've seen this webcomic talked about on this site, that I really knew nothing about its particulars.
The comic sets up a curious pretense of presenting itself as a game. As if you, the reader, were playing a video game (in this case like a point-and-click-adventure sort of thing) and interacting with the characters and their environment. I say curious because this is of course not true. The narrative is completely linear (as far as I've made it), and 'you' cannot do anything but progress from one comic to the next, the way any comic works. Except instead of a 'next entry' button, the link to the next comic is phrased in a way that implies you maybe entered some kind of text-based-adventure-style command like 'EXAMINE ROOM' or 'PICK UP [ITEM]' or what-have-you.
The comic buys fully into its own conceit, with our protagonist John Egbert (a name I'd heard before) interacting with the ostensibly real world in a game-mechanic-y way, storing items in his limited inventory* and recognizing the game mechanics explicitly, to make it clear it isn't meant to be a metaphor or somehow just for the benefit of the reader.
The narration is all in second person, and also follows the now-familiar style of video game text, whereby certain IMPORTANT TERMS are highlighted, such as names of ITEMS, and bespoke game terminology is used for actions. You don't put an item into your inventory, you captchalogue it into your sylladex, and if you don't have the right modus, then you won't be able to get to your items properly and you'll have to mess around to get it to work right.
Except of course, 'you' aren't actually doing anything. It isn't a game, it's a comic. In practice, the experience of reading Homestuck feels a bit like a choose-your-own-adventure game in which there is only one available choice at any junction. It's a weird sort of mix of the material inviting you to get involved, but always keeping you at arm's length to remind you that you can't. It's a keyfabe aimed at your suspension of disbelief in a very self-aware fashion, which is something I'll talk more about in my next post on this.