Thank you for sharing this wonderful Prelude-and-Fugue piece. Since I also compose preludes and fugues, I am very excited and interested in reviewing such a pair.
And indeed, I really enjoyed it and have now a few thoughts or comments which are not to be considered as „criticism“, but rather intended as an advice or idea how this beautiful piece could be improved further and finally made „great“:
When listening to the prelude for the first time, I clearly recognized the Baroque style of a French overture with its double dots and 32nd runs, but there were something stylistic that differed from a typical Baroque and counterpuntual piece. Now, after listening multiple times and with the help of the other comments, I figured out that this is due to the repetition of measures 1-14 in bars 15-27, which means that up to this point there is no real modulation away from the tonic G minor.
There is nothing wrong with it, but I would agree with the suggestions of @muchen_ and @Willibald to possibly change something concerning the modulation and recurrection of the material, also with respect that usually the prelude is not longer than its fugue.
The fugue subject is very memorable and expressive, I especially love the „wedge-like“ ending in mm. 68, which, in my opinion, implies that the theme should not end with the first eighth note in bar 68, but should extend over the entire four bars. In the comes in bar 72, you have already quoted the “wedge,” even though this bar is a variation of the original, while in the third entry in bar 76, the “wedge” is completely lost, which I regret.
In measures 80-85, 87-95, and 96-103, you have created three (or even four) sections with sequences based on different contrapuntal material—for example, quotations or parts of the theme—which would be perfect as interludes or episodes between further development (or exposition) sections of the fugue theme. And that is exactly what I would like to see: at least two further developments of the excellent fugue subject. I also could imagine a coda with a pedal point and perhaps a recurrection of the 32nd notes texture from the prelude as ending climax!
With this in mind – to shorten the prelude and to extend or „complete“ the fugue – your piece could become a marvellous pair – Prelude and Fugue in G minor!