Silent Hill: Revelation's original script was recently posted online, and oh boy, is it ever a doozy. If you like the first film a lot, I would recommend that you not read this, because it will piss you off. The retcons are absolutely astounding, and are everywhere, especially in the flashback sequences. The most notable of these is that the script claims Alessa was burned in her own home, and that she created the Otherworld during the burning by turning her eyes black and taking control of the fire. There are several other retcons, including Claudia being the leader of the Order when Alessa was young, Dahlia knowing the Order wanted to perform a ritual on Alessa to impregnate her with their god, Sharon being a baby stolen from its parents by Lisa Garland, and a bunch of others (though most of those others also appear in the final film).
Aside from the numerous retcons, there are some parts of the script that are better than what was in the final film, such as a scene of Heather calling for help, but no one being able to hear her. Other scenes are more of the slasher garbage that no one liked in the scenes that were included in the final film.
Yeah, this script is pretty depressing. Among other things, it proves that Bassett knew long before he made claims on his blog about not retconning the first film that basically the entire film was going to be a retcon piece. Like I said, if you love the first film, don't read this. It's positively depressing.
Also, the script implies that Vincent and Heather have sex in the motel.