Because video game items are made using 3D models, turns out it's not that hard to rip them out of a game and get them working with a 3D printer. And from there, bring something that previously only existed on the screen into the real world.
Angus from Maker's Muse has made this video showing how he pulled a weapon from Chivalry and printed it out. It's not life-size, but depending on the size of the 3D printer (and the quality of the game model) others could probably get bigger results.
While Angus' weapon of choice was a mace, the various pieces of software he used can rip objects from any Unreal Engine game, and similar programs exist for DirectX and World of Warcraft. And since he's ripping objects, as he mentions in the video, you could do the same thing for characters as well, creating your own figures.
I'm very tempted to set this up and just go nuts inside Deus Ex...