A work in progress (commonly abbreviated as W.I.P.) refers to any creation for the M.U.G.E.N engine that is currently in development, and is not yet ready for a final public release. Depending on the author, incomplete alpha or beta versions of the character may be released for the purposes of showing off progress or for acquiring feedback so that the character may be refined before the full release. Such incomplete releases may be released either publicly or privately to a select group of people (usually known as "beta testers").