If I recall correctly, the 2nd ending is the bad one, where instead of Heather returning to the "normal world" amusement park with detective pal Douglas, playing a sort of dark joke on him by wielding a knife and acting like she might kill him, and deciding to go back to her original name Cheryl before visiting her father's grave, we instead see her at the Otherworld amusement park (the series' sinister, twisted world where everything is super creepy) where she is standing in front of Douglas' bleeding body while she holds the murder weapon, having apparently been possessed by the demon god thing. It's been a while, but in short, the protagonist goes from happy and optimistic about the future to possibly possessed and definitely a murderer. And probably pretty used to killing things due to all that monster-killing you have to do to get the points to achieve said ending.

That is assuming the above person isn't apping from the super-goofy UFO ending.