Sidereals are the hardest splat to play of any of the ones I've played, though Fae are probably harder still.  Not only are you supposed to have celestial training since infancy (good luck roleplaying that without a good understanding), but you have to keep yourself completely secret, and Arcane Fate makes your very existence a pain in the nuts for the rest of the players unless the ST decides to handwave it.<br/><br/>I don't recommend having Sidereals in a game where other PCs are non-Sidereals, and this is coming from someone who occasionally plays renegade Abyssals.  Although, I may someday try again to run an all-Sidereal game, if people are good and really want it...<br/><br/>Now, granted, Shadow's already given his preference on it, but I thought I'd get that out there anyway.