Very impressive stuff, Dazzer. Nice job!
I'd be interested to see if you yourself can work out if it's playable, and fix what could be any really awkward places. Doesn't mean you have to be able to play it yourself, of course. But I'd guess that part of the art of writing a fugue (or fugato, semantics fans!) is that it should be playable. Maybe Koji could play it as is, but the composer should know for sure if it's realizable, no?
Keep it up,
Goose