First and most obvious is that the scale of the game has been brought down a bit. It will be a downloadable title from a smaller team so this makes a lot of sense. Please don't read that as a negative thing toward the game, but it is worth mentioning as to why the title swapped from a full disc title to a downloadable one. From the demo I played, I couldn't really tell if this will hurt I Am Alive, but at first glance I wouldn't have been able to tell if I wasn't told.
Second, and I actually said this to the guy before I knew who he was, the climbing and exploring is a lot like any of the Uncharted titles. As any of you who've played those titles knows is damn decent and by no means a slam. Yes, it does mean that there is nothing new in that arena, but really how many ways can you implement this kind of game play in a good way. Why complicate something that has been done well? Unless that is the goal I guess.
So by now you might be thinking 'what is the point besides the story?' This brings me to my next item, using intimidation as a weapon. Unlike some other post-apocalypse titles, IAA severely limits the amount of ammo and firearms since they would be coveted after a civilization ending crisis. Hells, I started the demo with a single bullet and had to use the threat to get as far as I could before using it. Some of the "enemies" in the game are just scared or trying to survive, so leaving them alone or threatening to kill them could bring about the same outcome as killing them. Quite ingenious. Especially since if you take your time, some might call your bluff forcing you to actually shoot. Interesting indeed.
If you are to conserve ammo so much, how do you take on the world? There is a melee system in the game, but it does have a bit of a curve and doesn't work as you would expect. For instance, it can only be used as a surprise attack or to defend yourself after antagonizing someone to much. There was no hack and slash action in the demo, even though you do pick up a Machete early on. This is to more or less enforce the social tactics more than physical, but it's odd not to have the option to just start swinging. That and when you are required to use it to defend yourself there is a small QTE needed that hopefully will be better explained in the full version of the game.
Now in the end, I enjoyed the demo with only a few gripes, but they were not something overly game breaking for me. But it does look like this will be a title that not everyone who was thrilled by the original announcement trailer. Partially because it is not the same game, but also partially because the game play mechanics do not seem for everyone. Maybe things will change here in the coming months, but I don't know how much since it is still slated for a Q1 release.
As a reward for reading all of the above, I now give you the announcement trailer for the game. Enjoy and keep an eye out for more info here.