The 2012 demo unlocks once you have completed the main game. It appears at the end of the chapter select. It is quite similar to the puzzles in Chapters 1, 2, and the start of 4 in the main game, so it should not prove too challenging given you have already completed those. I have put the solution in spoiler tags below in case you get stuck. I've broken the solution into sections based on which colour fruit you are collecting.
If there's anything I can do to improve the solution, please let me know in the comments before downvoting.
*** Spoiler - click to reveal ***
Red Fruit
As with the main game, start by moving the cursor over the central picture, then press 
to back out to view the scene through the window. Once the boy's thought bubble was settled on the monster, select it with 
, then select the two boys kneeling the bottom of the picture, then select the bowl they are holding. Press to back out, and watch the boy's thought bubble change.
Once he moves out of the picture, select the whole window by holding , and drag it to the upper right panel. Press to back out, then select the arrow in the bottom right of this panel. While the boy is getting the blue bowl in the panel, move the cursor back to the upper left panel and select the central building. Hold , and drag this frame to overlap the upper right. The boy will walk through the door and out onto the deck here.
Select and drag the upper right panel to the lower right. Move the cursor back to the upper right (the inside of the house) and navigate and into the room with the picture of the apple on the wall. Select this. Move your cursor back to the bottom right panel and select the bowl. When you have done so, a crow should appear in the upper left panel. Select it, and it will fly off the branch, dropping the red fruit into the bowl.
Green Fruit
Return the cursor to the bottom right panel with the boy, and watch the short thought bubble scene, then back out once with to see another one. Move the cursor to the upper left panel, back out once, then select the small buildings joined by a staircase in the left of the picture. Drag the lower right picture to the upper left and watch the boy climb in; drag it back to the lower right and watch him climb the stair to the left building in the upper left panel; select the door in the distance in the lower right panel to zoom in, then drag it back to the upper left. Finally, drag it back to the lower right again, and watch the boy exit and walk around the corner.
Zoom in on the boy and sign, watch him walk to the right, then select the arrow in the lower left when it reappears. Select the sign, and drag it to the lower left panel. Back out once to show the boy and the now empty sign, then drag the archway from the sign (should be in the lower right panel) over to this panel. Watch the boy walk through, then select the doorway to move to the next section of the puzzle.
Select the statue, then the bowl when the boy places it. Drag it to the lower right panel. Drag the revealed panel in the lower left to the upper right, where it should show the eye of the creature. Once the pupil has moved, drag the bowl from the lower right to the upper right, and watch the green fruit roll into the bowl.
Yellow Fruit
Press to back out, then select the arrow in the bottom right. Watch the boy's thought bubble change to a circle of coloured balls, then drag this panel back down to the lower right. Drag the revealed panel in the upper right to the upper left, then zoom in on the two people in masks carrying a chair. Drag this down to the bottom right where the boy is sitting.
Now select the building in the middle of the picture of the stairway between the two buildings with wheels in them (should be the upper right panel. The boarded window will now be open: select it, then move to the left, and zoom in on the horizontal tray with the tongs on the right of it. Return to the house picture in the lower left panel, and back away from the tree, and select the identical tray in the foreground. Drag this to the upper left panel, next to the zoomed in tray from the shed. A circular tin with the yellow fruit on it will roll to the left.
Drag the top left panel to the lower left. Return the cursor to the upper left, and back out once with to reveal the whole tree with the yellow fruit on it. Now drag the panel with the boy to the upper right, and watch him retrieve the yellow fruit.
Finishing the Demo
Zoom in once on the boy, and twice on the tower in the background of the upper right panel. Drag the upper right panel to the lower left, and watch the boy climb down to this lower part of the tower you have created. Back out once to see the creature appear in the background again.
Return the cursor to the upper left, and select the tower in the background with the angel on top. Press down when you can to see a train appear on the track. Zoom in once, then drag this upper left panel to the lower left to allow the boy to climb out onto the track beside the carriage. Then, drag this panel back to the upper left.
Zoom in twice on the illuminated window in the revealed panel in the lower left. Return to the upper right panel (the house), back out from the tray, and select the picture on the wall to the right, then zoom in on the golden ring. Drag this to the bottom left to make a coin. Move back to the upper left and zoom in twice on the red bar, then drag the coin from the lower left panel to the upper left to open the barrier and allow the boy to board the train.
After the short credits, your achievement will unlock!