Complex sentence: A 66 MB demo was released on May 10,2002, featuring the same level shown in an incomplete form at E3 2001, which did not feature in the final version of the game.
Split into simpler sentences: A 66 MB demo was released on May 10,2002. It featured the same level shown in an incomplete form at E3 2001 and did not feature in the final version of the game.