Hello,
I don't have much to say about the fugue itself, some disonant chords and transpositions to different keys is for me a bit unusual, but not necesarilly bad. My main remark is, that it is often almost or completely unplayable, good example is measure 24, whre it is physically impossible to stretch hands that much. I don't know how much are You familiar with harpsichord, but the thing here is that You don't have pedals to keep the tone sounding, so if You want the phrase to be going and sounding good and You need there to sustain some longer notes (so it'd "make sence in polyphonical way"), You must write it so the player can hold all keys needed, which here is, in some places, not accomplished. That's why there are often only 3 voices, when writing fugue for harpsichord; write it for four or more is of course possible but really hard to do properly and it is more common in organ playing, where You can use pedals as another voice.