Hi @Fugax Indoles. Nice fugue! I really like the subject and the countersubject. Both are very stylistic and have excellent features. The general musical grammar seems to be overall very good too (e.g. resolution of dissonances, treatment of melodic sevenths etc.). The following comments are made with the assumption that you aim to compose pastiche music in the Baroque style.
Let's dissect the rest of the fugue. Firstly, there seems to be a lack of subject entrances. Besides the exposition, I count a total of two further entries. One at the end in the tonic key, and another incomplete entrance in the rather strange key of D minor (which you turn to extremely often - why is that?). I feel like the piece could have done with a few more of those, particularly ones in major keys. Indeed you also seem to avoid major keys altogether here. Is this an artistic choice?
Now, the episodes. I don't quite understand some of the writing here. For example, mm. 11-15: it's not a sequence, doesn't feature imitative counterpoint, and it does not play on any of the rich motives present in the subject and countersubject. So what purpose does it serve? Another example is the dominant pedal in the middle of the piece. It's very nicely written and very dramatic, but what is it preparing us for? The resolution in mm. 31 seems to lead us onto more free counterpoint whose purpose I cannot quite understand. One possibility to remedy this is by tying all the bass B's in mm. 26-29, such that the pedal fizzles out over time. The less attention the pedal draws, the less ingenious the resolution need be.
Another point I'd make is that I feel the texture is too dense, even for a (mostly) three-part fugue. It's not necessarily that the voices don't get breaks, it's more that we are hearing three-part chords all the time, at more or less quaver or crotchet speeds, where the underlying rhythm are dominated by semiquavers. The best way of fixing this is to make extensive use of hockets throughout (see BWV 888b - arguably the best example out there) and by using notes of long lengths. It should help you to relax the harmonic rhythm too in certain places. Large chords being played constantly is especially problematic for the keyboard, since its sound production places emphasis on any newly played notes, as opposed to, say, strings, where the volume can be kept constant when notes are changed.
This brings me to the final point - keep the instrumentation in mind when you compose! This fugue is not possible to be played on a keyboard. The rule is fairly simple: each hand can reach an octave and maybe also a second very very occasionally. Even if you have no intention for this fugue to be live performed, writing idiomatically for the instrument is still good for the soul. It forces you to consider how to recreate certain desired sonorities with a more limited set of tools at hand.
Edit: forgot to mention that a tonic answer is required here, not a real one.