Complex sentence: Alien Attack officially opened to the public on April 14,2000, in the World Expo area of the park, replacing the "Back to the Future Part III" Locomotive Display which were relocated two years prior.
Split into simpler sentences: Alien Attack officially opened to the public on April 14,2000. The attraction opened in the World Expo area of the park, replacing the "Back to the Future Part III" Locomotive Display which were relocated two years prior.