This is the entire version of FNF Vs FNAF, which includes all four classic characters from the series as antagonists for you and BF to overcome. Assist FNF's BF in defeating the whole FNAF cast, including Freddy, Chica, Foxy, and Bonnie!
Whether you're playing in story mode or free play mode, the goal is the same: get to the finish of the tracks. To do so, keep hitting the notes until the song ends.
You must hit the arrow keys at the same moment in order for similar arrow symbols to float and match on top of the BF, but be careful not to miss too many times in a row or you will lose. Best wishes!