FNF: Great Papyrus and Sans

Game description:

In this game, you will fight at Sans's side in a musical battle against the Great Papyrus. The gameplay is as simple as possible - you need to press the shortcuts on your keyboard depending on which ones appear on the screen. The game features two modes - a story mode, complete with a storyline, and a free-play mode where the player's activity is limited to the music battle only. It's important not to lose your sense of rhythm, as a large number of mistakes will result in having to start the game all over again.