Jailbreak was the first of the MS Paint Adventures. It was created by Andrew Hussie with real inputs from his forum-goers at Gangbunch forums, later renamed to MSPA Forums. The adventure follows a couple of prisoners who, as the name implies, are trying to break out of jail.
Numerical data about Jailbreak are maintained here.
With a total of 134 pages it ran from the 25th of September 2006 until the 24th of February 2007 before going on hiatus until September 2011 where it was given a single page conclusion. It started as a small thread with only 2-3 suggestions per command. Only the first page of Jailbreak was done in MS Paint--Hussie gave up and resorted to using Photoshop. The first part ended with the suicide/game over, and a new thread was created for what happened afterward with elves and magic. The new adventure did not last long before Hussie moved onto Bard Quest (and a new site for MS Paint Adventures) so this part was lumped in together as Jailbreak. Hussie stated that one of the reasons that Jailbreak was not a success was that he accepted only the first suggestion per command, leading to a story that became too complicated for him to comprehend.
Jailbreak is fairly simple, featuring a Prisoner with nothing in his room, useful or otherwise, especially no large, orange, gourd-like fruits. The adventure then follows him on his quest as to what could be assumed to be him trying to break out of jail. Otherwise, you know, it wouldn't be called Jailbreak. Due to Andrew using only the first command given to him, many pages were dedicated to doing stupid tasks and much of the in-game text strongly suggested the players to input more correct commands the next time. Jailbreak introduced the concept of Arms and Pumpkins which still continue years after they have been introduced, and still have comedic effect. The concept of having multiple players was introduced - "You are now this guy." - But other than their bodily wounds, it was difficult to distinguish between the other "Guys". The Prisoners were more apt at mangling themselves than doing anything useful, and only one Prisoner managed to escape before he encountered the dreaded Tree stump. Fortunately, it is just a game, and the player was smart enough to select "Continue" to keep playing. The Prisoner then escaped rather easily with some runes on his stomach, the kind that could invoke elves and such. Before much more tomfoolery could pass, someone turned off the power to the game and never managed to finish it.
Many of Problem Sleuth's in-jokes draw heavily from Jailbreak, and they are the only two completed Adventures.
Also, it was later revealed that the Jail in which the majority of the adventure took place was situated in the Problem Sleuthuniverse when Zombie Ace Dick's whale crashed into the jail, causing the whale's death and sending ZAD plummeting into the jail itself.
It was then linked to just prior to Homestuck's End of Act 5, prompting confusion in readers everywhere. Andrew explained the intention was to give the readers a chance to refamiliarize themselves with the previous adventures. To do this, he made the 6000th page link to the first one before the 6001st page was released, "like a fearsome ouroboros, greedy for its own tail." Surprisingly, after announcing this, the second part of Jailbreak was given an ending. In the ending, the bedridden pony was commanded to enjoy a restful slumber, thus winning the game with a high score of 0 points. Briefly, this ending was removed and replaced with an even more oruboros-esque experience, where a false page (to give the player a blue, "unvisited" progression link) redirected the player back to the beginning of the adventure, as though the second trip through the story was within the pony's dream, and so on, ad infinitum, this was later reverted. The final page of Jailbreak remains missing in the Log, possibly because of its non-standard page number.
Recently, a page has appeared in Homestuck that is curiously similar to a page in Jailbreak. This has led to a mini-adventure reminiscent of the original Jailbreak adventures.