The actual
day of the
Second Impact,
September 13, 2000, is a reference to
Space: 1999. The
Second Impact happens exactly one year after the
explosion of a
nuclear waste disposal on the
moon in that series. So this
CD was released to commemorate the date of a
fictional event that was set at that date in
tribute to another fictional event.
The CD is actually very good. It is a sort of best of the best compilation, and though it contains no new songs that don't already appear on other Evangelion Music albums, that shouldn't stop you buying it. It is great for listening to in your car when you don't have a 20 CD stacker (becuase you will need one that big to hold all the Eva CD's) and you want all of your favourite songs.
Note: Evangelion - The Day of Second Impact is the official full title of the CD. See Evangelion Music for further information about namespacing issues.