Once you have chosen a tune to play along, your task is to play the melody on the keyboard, initially, by following what keys the program tells you to press (Single Key Play) and then, once you're good at it, by playing the melody all by yourself (Rehearsal Mode and Performance).
What's interesting is that there's a midi mode. Alas, I am not too familiar about MIDI interfaces for the C64 so hard to say if it's input (MIDI keyboard, doubtful) or output (most likely).
There's also a concert mode which might be a free-for-all type of deal.
Needless to say that the game portion of the soft is quite forgettable. On the other hand, Hearing timeless classics a la chiptune never gets old though.
Video above showcases tunes 1 to 6: Capriccio Italian, Caprice, Concerto No 1 Bb Minor, Dance of the Reed Flutes, Emperor Waltz, Hungarian Dance No 5.
Video above showcases tunes 7 to 12: Hall of the Mountain King, Minuet in G (Beethoven), Night Music Serenade, Romeo and Juliet, Sonata in C (Mozart), Toreador's Song.
Oh, almost forgot, check SID Sings post for a little blurb on this title, courtesy of Zzap! 64.