Hitman, although it's unique and has many positives suffers from a few problems, mainly bad AI. I've never played anything before Blood Money, but I actually liked the Operatic missions and settings.
Although I won't mind some reality settings (like being in a really bright florescent lit office or something), I like to play, instead of going for 100%, for style in my killings.
Replacing the WWI gun is stylish in its own, but why not also time your sniper shot with the actor's motions? (If I was actually making a movie, I'll show the audience 47 standing at the control panel, his figure outlined by the bright spotlight, and just when you think he's about to shoot the actor, boom! You see a gun chamber and smoke, but as the camera zooms out, you see the other actor in shock. And as the senator runs down, with the opera music continuing, and ironically following the script of the original opera, 47 prepares to shoot for real this time, and as he cooly walks out you can see the 2 lovers, almost like they were in an embrace, surrounded by blood.
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They need:
Better AI and social stealth
Less restriction and more open ranking system (does an agency care about the repair cost of the hotel, if you blow up an bomb in the target's suitcase?)
More open environment that allows for all types of assassination techniques.
