I believe that the game increases the difficulty of the minigames according to how many skill points you've invested. If you start off the game as vanilla Recruit w/out the jacked-up skills from word go, it's actually MUCH easier. Like, double the time and half the nodes/tumblers. It seems a bit odd at first, but when you think about it basing the game's difficulty off of the skills you have versus the level you have is a good way to keep the difficulty curve in check.
I wonder if there are values we can edit or use art money to change the weapons. like all values at 99, an Ultimate Weapon would be cool. Like super bullets, one hit kill, major explosion with grenades.
The only way i guess on how to kill Marburg in Rome museum would be when you get to Rome to do the following.
1) Kill NSA guy 2) Kill all CIA 3) Kill all even innocents on sniper mission 4) pick blue (Suave) in conversations with Marburg
You should then have acted recklessly enough for him to really hate you. ( I have not personally tested the above) But I know that Suave alone does not do it and he really dislikes you not being profesional and staying under the radar.