If they ever tried to make a Tsukihime anime, I would think it would be a lot harder. Didn't the Tsukihime game have a lot more story paths than the 3 of F/SN? I don't think that Satsuki really got her own storyline, though she is in several other ones. I haven't played it, but I believe that both Hisui and Kohaku had their own separate endings. That's two not including Arcueid and the main heroine, Akiha.