now that i've gotten SPAM working properly (and run through it a few times with a walkthrough), i can say for sure that this story is VERY early in development. here's an overview:
there's only one "ending" right now: you fuck ashley (she also informs you that she isn't actually into you, and it's just for the bet). nothing happens afterwards. also, her character still isn't set up for having sex yet, so you don't get any audio.
you can also get madison up to the room, but trying to fuck her doesn't seem to work right now.
rachel is just there as a plot device at the moment; she'll reject all your advances and you can't even learn what her secret is. you can ask her to join you when you choose one of the sisters, but she'll tell you she's leaving (likely out of disgust). the only interaction you can have with her right now is giving her her thermos (or some irish cream) and having her reveal the convo outside.
it seems like you can actually try to get both sisters at once, but that otion is broken and leads to nothing happening.
you can bring a sheet of LSD to the party, but you can't do anything with it.
oh, and sometimes it will bug and you can't use any interactions with your phone, preventing you from completing with the story. i wrote down my fix in another comment. you probably don't want to go looking for it, so here it is:
you need to have an amy character file in the story folder, and it needs to be otherwise identical to the phone call character file.
first, copy the file and rename the copy to "amy", then open the file in notepad and rename the "CharacterName" to "amy". then, laucnh the story.
if it doesn't work, close the game and re-open it. you may have to give it a few tries.
bugs and incompletion aside, i'm looking forward to how this story turns out. i'm hoping they keep threesomes as a possibility. threesomes are actually kinda possible right now; a guy on the eek forums even made a custom story with one!