On Twitter, Raven just announced that either Prop Hunt or Slasher will be added permanently into the game depending on the amount of retweets the posts get. There are two posts, one with a picture of Prop Hunt and another with Slasher. You vote with retweets. I do not have a link atm, but will edit this post when i get home.
(Please don't take this post down for having people go to Twitter to vote. Prop Hunt is on the line here)