Boyfriend wants to date Girlfriend. Unfortunately, Girlfriend's dad is a retired rock star who wants him gone, and so is pretty much everyone else she knows. The only way through is a rap battle. Then another. Then another. That is the plot of Friday Night Funkin', and it is all the plot a rhythm game this fun needs.
FNF began as an entry in the Ludum Dare 47 game jam in October 2020, made by programmer ninjamuffin99, artists PhantomArcade and evilsk8r, and musician Kawai Sprite. It quickly became one of the biggest indie games of its time, and because it is open source, it built a huge modding community. If you have played FNF XE on this site, this is where all of it started.

Arrows scroll up the right side of the screen. When an arrow overlaps the matching outline at the top, press that key. Hit it on time and Boyfriend sings the note. Miss, and the health bar moves toward your opponent. If it reaches their side completely, you lose the song. Long arrows with a tail need to be held until the tail ends.
In Story Mode, you play through "weeks", a set of three songs each against one opponent. You can choose Easy, Normal or Hard. In Freeplay, you can pick any song you have unlocked and play it on its own.
This version includes the full story, with every main week and the newer Weekend 1:

The soundtrack is by Kawai Sprite, and it is a big part of why the game spread so fast. Each week's songs have their own style, from the bouncy pop of Week 1 to the heavy beats of Week 7. Many players come back simply to hear them again.
For the modded side of FNF, try FNF XE. For more music games, there is Magic Tiles 3, and for a different kind of rhythm challenge, Geometry Dash. Now grab the mic. Daddy Dearest is waiting.