Thank you for playing! It was planned to let players customize both the note speed, and key configuration but didn't make it in time, to make things worse with the last update game update the note speed was set to 8 in a scale from 1 to 10 (that's the speed I often use in rhythm games but I agree it IS fast especially for easy mode). the spacebar choise was made mainly with hard mode in mind (polyrhythm being more prominent, so dividing the top and bottom notes between left and right hand seemed to be easier in that difficulty level).