I understand how to mark my clips as Legacy, but I'm wondering why it is necessary? I'm using Milkshape to create my models, and exporting to FBX for use in Unity. When I import as Legacy, everything is fine and dandy. When I import as Generic, it all seems to work fine in the animation preview, but attempting to use the clips fails completely during the game, with the warning that they must be marked as Legacy. I understand that Legacy mode is undesirable and so should be avoided, but right now I seem to have no choice. I have searched around and can find plenty of information about how to mark things as Legacy, but not any justification for why this is a thing. So I would like to understand why my animations have to be Legacy, and hopefully find out how to make them... not legacy. So that when Legacy support is eventually dropped I don't lose everything and/or get locked to an out-of-date version of Unity. Anybody got any ideas?