Here is the full list of all 14 BAD END achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Seen Ending No.13 "All my efforts were in vain"
Seen Ending No.05 "Not allowed to stop"
Seen Ending No.12 "Trivial mistake"
Seen Ending No.01 "Urban Myth"
Seen Ending No.03 "Forever haunted by fear"
Seen Ending No.02 "DON'T QUIT NOW...!!"
Seen Ending No.08 "BAD END04"
Seen Ending No.07 "BAD END03"
Seen Ending No.04 "BAD END01"
Seen Ending No.11 "BAD END07"
Seen Ending No.14 "TRUE END"
Seen Ending No.10 "BAD END06"
Seen Ending No.09 "BAD END05"
Seen Ending No.06 "BAD END02"