Ain't no game like this.
l still remember the first time playing it on Hard. l had some slight difficulties as in to get accustomed to it. But after learning it, it became second nature quite quickly. Even beated it more than 6 times. Non lethal too in some of the runs.
The story and most importantly, the writing is top notch. It has lot of implications, Michael is subtle when he tells such implications. You can tell he is tired of betrayal and people following orders to the letter, instead of thinking.