They way I got this was to make sure I went into every room to my left and right at least once before proceeding to the next room on the top. Sometimes in the rooms to your left and right there might be a new room popping up to go towards the bottom of the screen, which you otherwise might miss.
If you just continue to the top, it is possible to miss some rooms and also this achievement.
Playing it that way also assured me getting all the hostages in one game and the 1000 kills.
I also played in seed 1, don't know if it makes any difference if you do it in any other seed and of course I used the cheat menu mentioned in other guides.