Well done on a great tribute to Harold Ramis which manages to be fun and humorous, as well as subtly poignant. I think you did a great job in matching the dialogue between the characters with their personalities, and making the general mood feel a lot like the films. The story as a whole was very well written and structured even though it was quite short, and I felt a surge of satisfaction every time I got a gold medal. Oblivion was an interesting villain and quite creepy as well, I honestly preferred him to Gozer and Vigo, he just seemed to have a lot more personality. The music was great generally, loved the renditions of the film themes, they added a lot to the mood. The graphics fit the tone of the piece, and the character sprites were very expressive and eye-catching.
Overall, a great experience.
(incidentally, I noticed a glitch at one point in part one where Venkman's sprite was replaced with Egon's during the junkyard sequence, it's very minor, but just thought I should point it out.)