Music-based games typically involve some kind of abstract interface and a focus on rhythm.
In other words, they're often not particularly musical.
Lyrical Letters is notable, then, for its faithful focus on the core building blocks of any piece of music - the notes.
Lyrical Letters provides you with a faithful approximation of a cheap Casio keyboard, then asks you to listen to and repeat a simple sequence of notes.
The gamey twist here is that the sequence of notes will also spell out a word, and you can ask for a clue as to what that word might be.
Conversely, if you have no musical knowledge whatsoever, you'll struggle with Lyrical Letters at first. There's an easy mode, but the way it tells you the notes as it's playing the preview phase renders it pretty pointless.
The best thing you can do is stick at the game, because pretty quickly you'll start to learn the notes by ear. Before long, you'll realise that Lyrical Letters is essentially teaching you music.
On the plus side, you can select from eight different cheesy instruments, and it's also possible to record your own ditties and share them with your friends - though there are a whole bunch of more fully features musical apps out there if that's your thing.
Lyrical Letters is a pleasantly accessible, surprisingly educational (depending on your current musical ability) game-app hybrid. But it's unlikely to keep avid gamers occupied for all that long.