Off-Topic (abbreviated as OT) is a forum meant for the community to have conversations without any particular topic in focus. Threads can often be random, change topic, and/or have multiple topics simultaneously. Topics can range anything from daily life, opinions about the game, role play, jokes and meta content, nonsense, or anything in between.
The General Discussion subforum initially hosted any topic unrelated to gameplay that people wanted to talk about. As forum games started polluting the subforum, people suggested making a separate subforum for "self perpetuating threads".1 On 19 February 2009, peppy created the suggested subforum named Forum Games/Random.23
The new subforum created a distinction that General Discussion is to be used for serious discussions while Forum Games/Random is to be used for forum games and non-serious discussions. Given the nature of the Forum Games/Random subforum, people would often interrupt games hosted with random conversations.4 On 2 February 2010, Forum Games/Random was renamed to Off-Topic and the Forum Games subforum was created.5
Two more subforums would later be created: Mafia on 14 September 2011, and Surveys on 5 March 2014.
Given the nonsensical nature of OT, the majority of threads and discussions carried out therein are of very poor quality. Threads are rarely considered great, but when they are they are said to have reached valhalla.
The term was first used by Ephemeral in the ITT: We're Dirty thread, and subsequently a few times after. Since then, other people in the subforum have adopted the term.
Old Avatar Week was an annual event in celebration of the upcoming new year. Every year on December 28, people would change their avatar to one of their older ones for one week. This would remind OT regulars of an older time when the person had the old avatar, giving a sense of reflection between current times and older times like the transition from the old year to the new year.
People in the early Off-Topic days occasionally created threads dedicated to dancing anime girls. If a thread was bad, then posting a few dancing anime girls made it better. When people started making threads about quitting OT and actually not quitting, people took that as attention-grabbing and posted dancing anime girls to change the thread's topic. Posting dancing anime girls on any goodbye or welcome thread eventually became the common thing to do, and thus solidifying it as tradition.6
On 9 June 2017, Ephemeral asserted a slightly different version of the tradition into the Off-Topic rules by requiring people to post no less than 3 dancing anime girls on birthday threads. This made its way to osu!'s official rules7 up until 11 November 2019, when it was removed in a cleanup effort, but it still stands in the Off-Topic subforum's rules.
Exile is an unofficial moderation concept introduced by Ephemeral in the grand edict thread in response to people repeatedly spamming the subforum and creating otherwise annoying content. The exile system is enforced by removing any threads, and sometimes posts, by the person who is exiled. It serves as an indicator that the person is on the verge of being heavily sanctioned by more official means of moderation.
Since the Off-Topic subforum is composed of mostly the same regulars chatting among themselves in threads, everyone comes to know one another. Those who stick around long enough to be considered regulars are called "denizens". While this term was first used by Ephemeral in this post, it was not adopted by regulars until its popularisation by the OT!News thread series.
OT Lore is an effort started by abraker and perpetuated by other denizens to create an overarching narrative from the various threads people have created in OT. The culmination of this effort was compiled into the OT!Chronicles, which caused a time period in OT consisting of many improvised roleplay-related threads.
Thread derailment is a common occurrence in Off-Topic due to its nature of being "off-topic". This means that a thread created with a particular topic in mind cannot be expected to remain on that topic.
Despite the majority of OT being nonsense and miscellaneous content of unimportance, there are some notable threads that people unfamiliar with the subforum may find interesting.
This series of threads is a great way to get a sense of the highs and lows of OT without seeing most of the nonsense.
https://osu.ppy.sh/community/forums/posts/5942617
OT Court is OT Lore material involving a detailed imitation of an actual trial. Its organisation was improvised on the spot and, against all odds, it successfully lasted from beginning to end without loss of interest or being derailed.
https://osu.ppy.sh/community/forums/posts/6956061
This is a joke thread that has developed into OT Lore material. It is a great example of how denizens can create jokes threads about each other and then proceed to build narrative off the resulting interactions. It also demonstrate the unpredictable nature of how threads evolve and the nonsensical randomness that may come out of it.
https://osu.ppy.sh/community/forums/posts/7126163
This is one of several role-playing threads created as a result of OT Lore, that creates an interesting improvised narrative involving a mega-teletubby god that wrecks havoc upon OT and denizen efforts to destroy it.
https://osu.ppy.sh/community/forums/posts/7549082
Forum thread by lukewarmholiday (2009-01-30) "Separate sub-forum for self perpetuating threads?" ↑
Forum thread by peppy (2009-02-19) "Forum Games moved to new forum" ↑
Forum post by kuwarudo
(2009-05-31) in "Mis-quote The Person Above You" ↑
Forum post by Powerdrone (2010-02-03) in "Last person to see the 20 USD via Paypal thread" ↑
Forum thread by abraker (2022-02-20) "OT's Oldest Mystery: Dancing Anime Girls" ↑