LÖVE

There would be a separate theme for the menu and the game itself in a game i'm making, how do i make the menu music alternate to the gameplay music?

You would load both audio files with love.audio.newSource, play the menu music with love.audio.play, and, when going to gameplay, stopping the menu music with love.audio.stop and using love.audio.play to play the gameplay music.

Additionally, if you want a smoother transition between the menu and gameplay tracks by fading them in/out over time, you can either use love.audio.setVolume (to set the master volume), or individually set the volume for each track with Source:setVolume.