Cider is based on Wine, which is an implementation of the Win32 API on Linux.
Both share a common codebase.
The problem with Wine, Cedega, Cider, etc. and Aion is, of course, that stupid rootkit that NCSoft include with every game:
GameGuard.
To support Aion on Mac/Linux they have to drop GameGuard, because it is a device driver for the Windows kernel only.
It also cannot be uninstalled, even uninstalling the game. And it keeps running when the game stops, using CPU resources, and hiding itself, so you never know its real CPU/mem usage.
You can read more at the Wikipedia entry for
GameGuard.