Playing the game and skimming over the comments other folks have left, I can safely say others have done a great job summing up my thoughts on your work. Thus far, this is the most polished game I've played. From graphics to sound to completely different play styles depending on your chosen ability. It all just works wonderfully.
Personally, my only beef is with the controls. Specifically, decades of using my left hand and WSAD to move has made controlling character movement with my right hand a bear. For me, it was like throwing a ball with my non-dominant arm... I suck at it. While I enjoyed my time with the game, it was a struggle due to those decades of muscle memory (or, I suppose lack of muscle memory with my right hand). I think I would have enjoyed the game even more if I could move using my left hand.
My one beef aside, you did an absolutely fantastic job creating a wonderful game. Well done!