How do I make mein leben even harder

I have completed mein leben difficulty multiple times and most of my game's playtime is from it. I was looking for something more difficult and challenging ways to complete mein leben i thought of doing something like a pistol only run but I think it wouldn't be possible for multiple stages like the courthouse and the very first mission, if anyone knows how i can increase the damage multiplier on enemies or have any ideas please suggest me thank you.