Naming notes and playing a piece are two different skills. You can identify every note on a staff and still freeze when it is time to play, because playing demands the right pitch at the right instant, with no pause to think. That leap is exactly what this game trains: the score of a real piece scrolls across the screen and you play the melody.
There are two modes. Practice stops the score at every note and waits for you to play the right one: it is for learning the piece, and nothing is scored. In time lets the score run with a metronome and measures your playing — the right notes, and how precisely you attack each one. The tempo is yours: a 30 to 160 bpm control lets you learn the piece slowly before taking it up to speed.
You can answer on the on-screen piano, on your computer keyboard, on a MIDI keyboard connected to your computer, or by playing into your microphone. With the microphone only pitch is measured, not rhythm: pitch detection lands after the attack, so timing it would mean inventing a precision that is not there.
The piece is the Happy Birthday melody — "Good Morning to All", 1893, in the public domain. Melody only, no lyrics. A tune everyone knows by heart helps more than you would think: when your reading goes wrong, you hear it straight away, no scoreboard needed. It runs right in your browser, on a computer, tablet or phone, with nothing to install.