Ok, Deus Ex 1 is probably my favorite game that has withstood the test of time and all, and Deus Ex 2 was one of the biggest disappointments I have ever experienced.
So now to the trailer. First of all, no gameplay in it at all. Second, too much badass without any actual badassery. Deus Ex 1 you had the ability to kill everyone if you wanted to, on top of the ability to go by unnoticed. I like that there seems to be more melee invlved in this game, DE1 just has the Dragon's Tooth sword, but it also seems like it will be even more action oriented.
In terms of gameplay for this game not to be a huge diappointment it will need to be an open world level game just like the first, where you can approach you goal in a near unlimited number of ways. Kill everything, sneak by, hack in, etc. etc. This trailer showed nothing other than the first of that list and that's why I am even more worried.
In terms of story, the original did not come right out and started to blame corporations, you revealed all the consipracies as the game progressed. You had the plague and worked for UNATCO at first, and everything unfolded from there, leading you to discover the illuminati and their global plans. It wass basically a B-rate crime novel. Which is absolutely amazing for a video game.
This one seems to throw you right in with all the conspiracies and everything. That is going to be a pretty big disappointment and it looks like it will give you those shitty atempts at "choice" that so many games nowadays seem to give out in terms of how the story goes. If they do that, it must be at least as good as ME at consequences for choices, but it will still be hard to match up to DE1's good story, for a VG. As you can remember, ME's story is very meh.
Overall, this trailer has me a lot more worried that DE3 will be just another entertaining mediocre game and not the amazing groundbreaking formula that DE1 had, which has yet to be copied in any game.
