We've already seen Abylight's Music On: Electronic Keyboard application for DSiWare, a decent but flawed attempt at putting a keyboard in your pocket. Now the company's back with Music On: Retro Keyboard, and although it shares the first game's finer features and faults it's a better buy overall.
As with its predecessor, you're granted a two-octave keyboard that starts from C or F depending on which layout you prefer. There are touchscreen buttons to access higher or lower octaves, though sadly no way to do this on the fly, though you can use an ad-hoc pitch bend feature that gives interesting results.
One of the problems with Electronic Keyboard was the five voices were a bit hit-and-miss, but Retro Keyboard avoids this by using decidedly old-school sounds that will be instantly familiar to anyone who's ever gamed on a classic system: the triangle voice is straight out of Donkey Kong, for example, and other classic games have clearly inspired the other voices. Whereas Electronic Keyboard offered real-life instruments voices at higher sample quality, Retro Keyboard includes sixteen voices of lower sample quality that are just more fun to play with. In no time you'll be having a blast trying to recreate famous gaming tunes of yesteryear.
The accompaniment styles are all inspired by classic games too, though as with the predecessor there's no way to play a chord without using a background style which may frustrate some budding musicians. The record function is identical to that in Electronic Keyboard too, meaning no ability to layer voices in one recording. This isn't such a problem when trying to recreate old-school tunes as they tended to have limited audio channels, but it's still a shame.
With a retro-styled interface and sounds to throw any gaming fan into a fit of audio nostalgia, Music On: Retro Keyboard is simply more fun than the serious Electronic Keyboard. It still suffers the same limitations in terms of recording, and the DSi's lack of multi-touch is an issue that may prevent further releases reaching their full potential, but this is a fun little application that will entertain even non-musical gamers.