HarmoKnight (Rhythm Hunter: HarmoKnight in Japan) is a rhythm based running, jumping and whacking game. You play a boy named Tempo who is fighting enemies with a musical note staff. You are joined by an archer named Lyra, a buff warrior named Tyko, and his monkey companion, Cymbi on a mission to save the princess.

You automatically move through side-scrolling levels and must press two different buttons to jump and swing the staff. Do this in time with the music and you gather notes to progress. You can charge your staff to earn extra notes as well as choose different routes through the levels to find bonuses. At times you switch to other characters to use the crossbow, harder hits or ride on karts.

If you are hit by an enemy or obstacle you lose a heart and fail if you lose them all. You are graded at the end of each stage based on how many notes you have collected. As levels are unlocked you discover different themes and musical timings, 4/4, 3/4 and so on. You can unlock some stages that feature music from the Pokémon series, that this developer created. At the end of each set of levels you take on a boss fights, with harder and more repetitious timing required.