Instruments are fairly common devices in MS Paint Adventures, their typical purpose is the creation of music, however they tend to be used in often multifaceted and somewhat unexpected ways. Instruments typically seen are of the brass and woodwind nature, such as Oboes, Bassoons, Trombones, and the like.
In Bard QuestEdit
In Problem SleuthEdit
There is a piano in the jazz room. Instruments serve as a way to solve weird puzzle shit, helping Problem Sleuth get a note to continue on with the game. Instruments can serve as weapons for the Legendary Jazz Musicians, as they attack with their horn based onslaught against Morthol Dryax. The Clown Bard uses a Lute to bust out incendiary Lute Solos and attacks through the use of his skilled playing. Instruments are also used as security devices, as they can be wedged between doors to keep things shut. It's universally accepted, as shown by a myriad of characters, that an instrument is the best way to keep people from just walking around all over the place.
Each of the Homestuck Kids is associated with a musical instrument: John and Jane produce haunting refrains with the piano in Dad's study, Rose saws quickly on the violin she carries, and Dave and Dirk mix beats on a turntable. Jade makes noise with a flute she found, but is hauntingly relaxing on her Eclectic Bass. (It is not yet known what instruments, if any, Roxy and Jake can play; however, there is a violin seen in Roxy's room on a shelf above her mutated cats. For symmetry reasons it can be assumed Jake plays the bass as well.) John's piano was broken as a result of Rose's server-side attack on an Imp riding the Green Slime Ghost Pogo, but thankfully no other instruments have suffered this fate.
The pre-scratch kids' instruments seem to be related to their abilities. John uses the Hammerkind specibus, and plays the piano, which works by hitting strings with hammers. Rose uses the Needlekind specibus, and plays the violin - both of which involve yarn or string. Dave's instrument is not related to his specibus, but to his status as a Hero of Time - he learns to master stable time loops and handle many things at once, which is similar to how one uses a mixing table. His time turn-tables notably look just like his mixing tables. (Dave's Bro later does use a blade on a turntable attempting to initiate the scratch.) Jade Harley uses the Riflekind specibus and plays a flute, both of which are long metal tubes. Additionally, her Eclectic Bass is an instrument too complicated to play without the aid of robotic extra arms, and she also dabbles in robotics.
John's instrument is the key to opening the chamber of his Denizen; there was a pipe organ carved into the rock face of the entrance chamber to John's denizen's lair for him to play the song required to enter. It is unknown whether this is the case for anyone else.
The dream bubble's pirate crew played a variety of instruments as well.