If you'd like to jump right into reading something, I think Problem Sleuth is a good place to start, personally. But it's a pretty long read, so be sure to have the save game feature handy!
But before you jump into an adventure, a little background on the site would probably help. There are two key points to understand! They are:
1) MSPA stories exist in the format of "mock games", specifically text-based adventure games. You advance through the pages of the story by clicking links which sound like commands you would type in a text prompt to get a character to do something. Generally, the character will respond to that command on the following page.
2) MSPA stories are largely "reader-driven", in the sense that most of the text commands were supplied by readers through a suggestion box. I would select a command from the list, and then illustrate the result of the command.
When I say "largely reader driven", I mean this approach has undergone a lot of evolution from adventure to adventure, and continues to even now. I'll try to give a sense of what the process was for each adventure.
Jailbreak: This was the first adventure, one I started well before the MSPA site existed. I created it on a forum, where people would post suggestions in replies to the thread. My policy was to always take the first suggestion no matter what, which naturally lead to a very haphazard feel to the story's progression. I also experimented with "branching" the story at one point, splitting it into two paths. But then I quickly brought those two paths back together.
I left Jailbreak unfinished. And it's probably fine that way, as a sort of rambling, silly initial experiment with the storytelling format. I doubt I'll go back to finish it.
Bardquest: This was the first adventure I started after launching MSPA.com, back when I had the "choose your own adventure" format in mind for the site as the primary storying device, in addition to the reader-driven feature with a new on-site suggestion box. But the multiple paths turned out to be quite difficult for me to keep up with, and overall, probably pretty hard for readers to digest as well, especially with a longer story.
Mercifully, this one never made it that far. I chalk it up as an interesting failed experiment, and one that I surely won't go back to finish. After halting BQ, I left the site to gather dust for about six months, then started it up again with Problem Sleuth.
Problem Sleuth:By far the longest adventure (Homestuck is now much longer), and only complete one to date. When I started, I revised the approach, completely scrapping the multiple paths concept except in a few minor instances. I also started being more selective with the suggestions, not necessarily always picking the first one in the box. This made for a more controlled style of action, allowing elements of planning and puzzle solving, while still creating a pretty whimsical feel to the adventure.
But I feel MSPA evolved in many more ways than that over the daunting span of Problem Sleuth (exactly one year, in fact). The nature of the parody drifted away from text-adventures exclusively to playing off many other sorts of gaming genres, like RPGs, fighting games, etc. The visual style progressed as well, as I started incorporating more and more animated frames and over the top battle sequences. And the reader-driven element shifted very gradually as well, especially as the story took on more readers.
When a story begins to get thousands of suggestions, paradoxically, it becomes much harder to call it truly "reader-driven". This is simply because there is so much available, the author can cherry-pick from what's there to suit whatever he might have in mind, whether he's deliberately planning ahead or not. But as it happened, I was planning ahead much more as the story neared its end, and I would tend to A) pick commands that suited what I had in mind, or B) just call a spade a spade and outright MAKE UP a command for an idea I had, which I did most often for many of the later attacks (like the Sleuth Diplomacy variations, Comb Raves, etc).
Toward the end, the suggestion box was mostly used as a go-to for the frivolous, funny tangential stuff, and rarely anything story-changing. I've come to view this as the only realistic practice for a site with this format, with this many readers. This practice carried over to the next adventure, right from the start.
The adventure I'm currently working on, with a pretty radically different approach from the way the previous adventures started, mostly in the sense that many elements are already preplanned. I don't know if I intended to make a big point of this as huge a paradigm shift for the site. It was more that I started getting ideas for the next adventure well before Problem Sleuth ended, and those ideas just kept cropping up. Much like with crafting the conclusion for Problem Sleuth, the planning just couldn't be helped!
So the use of user commands has been handled in a similar way, insofar as they contribute to a direction I want the story to go in, or to simply produce a humorous tangential effect (which can sometimes lead to story developments I don't anticipate anyway!) But the point is, the reader-driven aspect of MSPA is still in a state evolution, and truthfully is probably drifting away from being a very important factor in the way the story is structured.
It is manifesting in other interesting ways though. With HS I introduced the incorporation of music into the story, and the production of this music has been a collaborative effort among readers. Other ideas and resources like funny images, game mechanic concepts, etc, have made it into the story outside of the institutionalized structure of the suggestion box. I also picked the characters' names from reader input. There are lots of ways I will inject reader input into stories, and finding out how will be the fun part. But it will almost certainly never resemble the madcap charades of Jailbreak or early Problem Sleuth.
The bottom line is, the MSPA format always seems to be in a state of flux, and I will surely continue to bend my own rules in various ways. Honestly at this stage, I am less excited about the reader-driven aspect than I am about the format that has emerged and somewhat crystallized, which is: telling a story through the vehicle of a mock-game, complete with somewhat convincing and detailed mechanics, but without losing sight of it as a parody. That format has been augmented with the use of Flash animations and interactive pages, which is something I'm sure I'll keep exploring.
Anyway, if you really are a new reader, I guess that was a lot to digest! But even if you're not a new reader, I'm sure you gleaned some insight from that.
If you go by page count, Homestuck is about 99% done. The remaining 1% will involve another stretch of pages, and some heavy animation work. Site is currently paused while I catch up with some other work, and finish the remaining pages of the story.
Starting now, We Love Fine will become the primary seller of Homestuck products. Almost everything from the What Pumpkin store is in the process of being moved over to the We Love Fine store. We're also working on a lot of cool new things, which will show up in the WLF store over the following months.