The major challenge was using non-lethal force all the way through the game. It even counts during the prologue, no deaths whatsoever is exactly what they mean. I tried to stay hidden and sneak by most of those initial enemies, but there were a couple times when it just was not possible. Scripted events that trigger when you hit a certain spot are fine for a tutorial, but frustrating when you're attempting to slip through without notice. The one in particular I'm thinking of really had me irritated, even after several reloads I couldn't manage to sneak by without alerting at least one enemy. As soon as you get midway into a fairly large room a bunch of enemies appear through the far door. Of course if one sees you and goes hostile, the others are almost instantly on to you as well. I made it through the exit door a few times, only to be shot in the back just as I'd round the corner.
After that slight bit of initial frustration the game became almost cake for awhile. A skilled player familiar with stealth tactics from other games knows it's just common sense to stay low and keep quiet. There are augs you can get to help with that, but honestly I didn't even waste the points. Using cover and the environment, I was able to silently move around an area and take each guard out one by one. It was time consuming, but my obsessive nature wouldn't let me leave an area without hacking every device and searching every corner for hidden paths or objects. Just like the original, Human Revolution is full of air ducts and vents to crawl around in. Just about every time I was faced with a group of enemies, I would move a crate or box and find a vent to crawl through that would bypass them entirely.
After hacking and the typhoon, I tried to invest in other augmentations that I knew would help my play style. A couple of those are absolutely necessary for any play through, at least in my opinion: the Icarus landing system let's Adam fall from any height without taking damage. It may not seem like that big of a deal, but after getting to China I realized how useful it really was. I ran across several areas with no ladders or elevators, just a straight drop to the bottom, which means death without Icarus. Plus it's just really cool to watch; run and take a flying leap off a building, then watch as energy pulses slow your fall.
Another one I couldn't live without is the arm aug that allows Adam to punch through weakened walls. There were a few spots in my first attempt that I couldn't do anything with because I didn't have it. You can still blow through them with explosives, but really that's just a waste. The only downside with the aug is, as expected, it makes alot of noise and has the nasty side effect of killing anyone who happens to be standing on the other side. Since I was playing as a pacifist, this was not a chance I could take. As if in answer; one of the eye augs allows Jenson to see enemies, security devices, and computers through walls. Not really that useful for a combat specialist, but invaluable for someone using stealth.
In general I tried to do every side quest and leave no stone unturned, but somewhere around hours 35-38 that went right out the window. The last area has Adam trapped with lots of enemies, most of which are impossible to avoid. They can be killed easy enough, but obviously that wasn't an option for a pacifist. By this time I had burned through most of my gas grenades, plus they were grouped together so a stun gun or tranq rifle wouldn't work. I ended up using the cloak aug to try and run past, which worked for the most part. It sucks to run out of energy in the middle of a mob, but I guess that's what quick save and quick load are for. Although it's not required, there are a couple major characters in the last area that you are supposed to go "save" before heading down the elevator to the last boss. In my haste to reach the finale I skipped one, so I didn't get to see all four endings. Oh well, gives me a reason to go back and play through it again in a year or two.
Deus Ex : Human Revolution is without a doubt my GOTY as of right now, but there are quite a few other big titles coming later this year that may unseat it. Regardless, it's one of the best FPS RPGs I've ever played, easily as good as the first and every bit a worthy successor. I can't wait to see what they do for the sequel.
