Reference

物理演算ドミノ - Engadget Japanese
http://japanese.engadget.com/2006/05/25/ingame-physics-domino/

物理演算パズルArmadillo Run：ピタゴラ装置も作れます - Engadget Japanese
http://japanese.engadget.com/2006/07/05/physics-game-armadillo-run/