Puzzle Storm: https://lichess.org/storm
The influence of pitch feedback on learning of motor-timing and sequencing: A piano study with novices: https://pubmed.ncbi.nlm.nih.gov/30485336/
Note: Mike got some details wrong in his retelling of the above study. There were 3 groups of subjects, not 4 (there was no group tested where the piano was silent). The overall point still stands, but regardless, sorry about that. He got a little too excited.
