Recently the first boss in deus ex human revolution, I was on my first playthrough on hard difficulty(or whatever it's called) and I had chosen to do a stealth run investing all my skills into stealth based ones and I didn't carry many weapons as they just took up inventory space on me since I would probably just end up running, then comes the first boss...he has a ton of health, deals a ton of damage (especially when you're like me and have no health/armour upgrades), I spent hours trying to kill him but my few guns+grenades were useless against him and even when I hit with all of them they didn't hurt his health enough to kill him, and whenever he caught up to me he literally killed me in one hit, it was a long and tedious bossfight and even after I beat him I didn't even feel accomplished, in fact I wanted to turn off the game before I reached the next one...