EDIT: As of Feburary 18, 2015, GamerByDay has managed to restore the achievements the game had to begin with, but I still cannot recommend that you buy this game or support Mumbo Jumbo until the issue is fully fixed.
Frankly, the fact that it took almost a whole year - from March 2014 when people began reporting issues about the broken achievements to February 2015 - for this issue to be fixed is rather baffling, to say the least. Not helping Mumbo Jumbo's case is their lack of action to fix the problem when it first came up, and things only went downhill after they deleted the achievements and (initially) refused to restore them. It should also be noted that two other Midnight Mystery games (Devil on the Mississippi, Haunted Houdini) had the same update process as Salem at the same time, so why Salem was broken and why Mumbo Jumbo didn't bother to fix it before things got out of hand is, again, baffling.
I'd keep a wary eye on Mumbo Jumbo and their games and check the forums to see what's going on before you give them any money. You are free to read the original review below.
ORIGINAL REVIEW FROM FEB. 14, 2015:
I cannot, under any circumstances, recommend this game. Additionally, I cannot recommend purchasing any games from Mumbo Jumbo. I'd advise to stay FAR away from Mumbo Jumbo after they removed the achievements from this game, a feature that was the incentive for me to purchase via Steam rather than, say, Amazon or some other digital storefront.
MumboJumbo is too lazy to fix this game, in particular, and rather than put in the effort to listen to customer feedback and implement fixes for what they broke to begin with, they would rather REMOVE features and further break their games. I have noticed whenever they updated their games on Steam, there are no notes or documentations on what was done to warrant the update.
I would only follow Mumbo Jumbo just to make sure if they bring any more games to Steam I can be sure to avoid Mumbo Jumbo's games like the plague.