Wrote this just for fun.

Any feedback/tip will be useful

midi_piano_miniature.mid

Hi @Cafebabe and welcome to the forum!

This is a very quirky and unique piece!  Some parts of it remind me of Mozart, others Scarlatti.  You have some quite adventurous modulations in this!  Some of your harmonic choices take some getting used to and I find the retransition back to the main theme in meas. 16 - 17 lacking (you just stop one section in C minor and suddenly return to the main theme in D major - quite distant if you consider Riemann!)  I would definitely call this a sonatina in development!  But in order for it to be fully fleshed out you really should fashion better transitions between each of your phrases.  There are also some awkward enharmonic spellings such as the B# diminished chord in meas. 10, 3rd & 4th beat.  As it is the piece is definitely succinct and action packed, erring rather on the side of variety rather than unity in that precarious balance that all composers must strike.  It's enjoyable as is although I feel like if you put some more work into it, it could really be a much more consequential piece.  Or you could keep writing short pieces like this, learn from each experience and develop your craft that way.  Thanks for sharing!

Peter