Here's a tiny look at how the designers play a level before all the beautiful art gets put in.
In this video, we're doing some audio tuning to one of the more chill songs in the game. You'll notice small grey squares where enemies and level elements should be. You'll also notice very basic artwork that we use for all of our levels that don't yet have any level-specific art.
But since the designers need to finalize the level's environment before the artists tuck in and make it pretty, we start putting stuff together once we get the songs, regardless of whether we have everything else that will eventually make this level whole.