There is a very easy way to get this achievement, although it is essentially cheating. You can simply type “ending a1” into the console in keter difficulty and it will pop. Note: you will have to go to settings > advanced > enable console in order to be able to access the console. Once that setting is active, just press F3 in game.
Otherwise, be weary of the permadeath and calculate every move. It will be pretty much impossible to beat the game if you don’t contain SCP-106, so that should be a priority. You can look up how to do that elsewhere or there is a note explaining it in his chamber.