well, Unreal is notoriously bloated irc daemon which became relatively popular in the recent years, primarily among people who would rather enjoy useless bells & whistles ("features") than clean, streamlined ircd design and stability
and QuakeNet's asuka is basically an ircu clone (ircu is Undernet's daemon), renamed for whatever reason and used on everyone's favourite bot-, spam- & drone-friendly network
that's not true, afaik ircu is simply what they use for a base and asuka is alot of addons etc..
When you connect you also get u2.10.11.07+asuka(1.2.1)
u2.10.11.07 being ircu and asuka being a sort of patch to make it nicer :p