Friday Night Funkin Starlight Mayhem Mod is a free online rhythm game mod available at fnf.gosprunki.net. In this full week mod, you battle against CJ and RUBY in front of everyone on a big concert stage. The original mod can be downloaded from GameBanana (mod ID 287114).
Director and artist: TheMaskedChris (GameBanana member 1821498). Coding: ash237 (1813477). Charting: Cerbera (1816058). Vocals: Ridinginthered (Twitter @ShockLocked) and Miyno_ (1782926). Instrumentals: Mudstep (YouTube).
If the game is too laggy or glitchy, click the green flag lots and lots of times to help the game work properly. This is a common fix for Scratch-based FNF games.