To unlock and play the 2012 demo: After beating the normal version go to the far right end of the chapter select screen. You can choose the 2012 demo there.

It's not on my menu... Do these options disappear when you get a new computer because I find most games just undo any progress I made when i get a new computer so I'll have to replay games from scratch just to do something simple like getting access to this damn demo, which is kinda not worth it.

you must beat the game first, after that the demo unlocks.