So I've finished the main story, can see Desperate Measures listed in 'Jensen's Stories', there's an icon hovering on it as though I can select it, but when I hit X, nothing happens.

Reading online it looks like it was initially part of the Augment Your Preorder thing, then it was going to be offered for free? I can't seem to select it and it's not on the DLC/Shop list either.

I just don't get how to access it, and feel like I'm missing something really obvious haha, any help is greatly appreciated! Thank you :D

Maybe it's only available if you pre-ordered the game? Don't worry, you're not missing much. Strange that they would tease you with it showing up in the menu, though.

Did you get a code in your box / with your steam key? If you did you can register your game on Square Enix's site and they'll send you a code to download it.

Here's what you're missing. It's a somewhat short mission with very little story about a security guard covering up his brothers involvement in the train bombing.

Hm... I didn't preorder the game, just got it first day. In the box (if you got it retail), there is a code on a small piece of paper you'd be able to put in on the Square site, which gives you a PSN or Live code which gives you some weapons, and the Desperate Measures mission, what have you. BoOzak has already explained it all. It's kind of weird why they'd put this in, and not just into the main game, as if they didn't have time to put it in the main game or something. I don't know, it's just weird. The mission is just you going through a new area, and finding someone that tampered with footage of the bombing. It's really not much; it's about as long as the bank side mission where you have to find evidence of Picus' wrongdoings, and really just similar overall.

It's a very short mission that clarifies a VERY minor part of the story. You won't be missing out much.

I had some issues starting it as well, i think the UI was pretty bad. And this might not work for you i have no clue. But Its says with big letters Jensen's Stories, right under that there is a subtext which says Desperate Measures with a arrow pointing down. You need to click that i think, or maybe the Ready to Play thing.

Either way, you aren't missing anything. its a pretty throw away thing. And nothing carries over.