Assuming Nicholas's death doesn't affect his father's reign, and the throne is simply passed on to Alexander III's next son, George, in 1894. George was very sick with chronic tuberculosis, and was forced to reside in Likani when his father died, away from St. Petersburg, and he stayed there until his death in 1899. I'd imagine he'd be moved back to St. Petersburg for coronation and rule. I personally think his chronic illness, and lack of training would prevent him from ruling to the most of his abilities, despite being 'cleverer' than his elder brother Nicholas. His reign would probably be dominated by the characters who were strong during his father's reign, with perhaps less commitment to autocracy, the specifics of which I cannot comment on because I am not knowledgeable enough. I'd also venture that George would die young, as account of his illness, to be succeeded by his younger brother Michael, probably around the turn of the century, and that is probably where it gets interesting.