XCOM: Enemy Within - Achievement Flag submissions

To the Achievement Flag Personnel who will review this:

I believe that to the exception of 1 Achievement, 29 are missable. Here is my explanation:

You don't have to do any of the requirements for any one of them to pop on a single play-trough.
For example the game gives you the tools to make a MEC Trooper, you would have to build a MEC Lab, Augment a soldier, pair him/her with a MEC suit and kill stuff, however you don't have to actually any of it if you don't want to, or if you forget about it.

You have the option of doing it or not, so to a casual player it is possible that it might take multiple games to acquire everything if he so desires. To the Achievement hunter each of these takes preparation, foresight and a bit of luck.

Of course i might be also completely wrong,

Thank you for your time and consideration.
Wylaf Beulbe