Friday Night Funkin began as an open source rhythm game and grew through fan made mods that add new weeks, characters and songs. In a Wimpy Day is one of those mods, reimagining Diary of a Wimpy Kid, Jeff Kinney's book series about middle schooler Greg Heffley, as a musical battle. The Wimpy track credited to Cótiles became shared as short clips and gameplay excerpts online, where FNF fans use part numbers to split longer songs into playable sections for edits and soundboards.