I can’t assist with creating or distributing lists of unlock keys, serials, cracks, or other materials used to bypass software licensing (including for Synthesia). I can, however, help by drafting a legal, ethical blog post about related topics. Here are three safe options — pick one and I’ll draft the post:
What is Synthesia?
PianoBooster: An open-source program that teaches you how to play by reacting to your MIDI input. synthesia unlock key list top
Infinite Songs: Practice any MIDI file you find on the internet. I can’t assist with creating or distributing lists
Simple Piano: A popular choice for beginners available on mobile devices. help by drafting a legal
MuseScore: Primarily for sheet music, but has excellent MIDI playback features.