The instruments I currently own & can play are:
flute, recorder, various whistles
zither (two-octave, diatonic)
melodica
drums

I've been saving up for a concertina for a while, so that's probably going to be the next instrument I attempt. But what I'm really missing is something that would play notes - preferably more than one at a time - with a percussive attack & decay, rather than sustained notes a la melodica (or concertina).

Basically I want a piano - BUT
(a) I've got nowhere to put an upright, even if I could get one cheap and in good condition
(b) I don't want an electronic instrument (all my instruments produce sound by hitting and blowing, & I'd like to keep it that way)

Is there such a thing as a percussive acoustic keyboard instrument, that's not a piano?