Many camera based games tend to be quite unskilled. This was an attempt to make a game mechanic which required a lot of practice to master.
The game mechanic worked rather well. However, we never really got the head tracker reliable enough to use it. It isn’t enough to just track a head, you need to be able to detect when it has erroneously detected a spectator standing in the background too.
Before working on Wonderbook, I worked on EyePet. An augmented reality virtual Pet game for PlayStation 3.
The game was shipped with a “Magic Card” which was used to move objects in the game work around in 3D. This was before the PS Move controller was developed. The Magic card uses the fiducial marker system which was later used in Wonderbook. Since this was not tolerant to occlusion, the card had to be physical designed so it was always held without the players hands covering the marker.