This sugsestion would be hard but, it would be really afective if the dominoes behind the first one with the purple where falling and adding motion to the picture.
dominoes rock, did you change the levels to make another color (like red?) into the purple though? There's just something a little not-real about the looks of things.
Interesting concept... I think lighting plays a really important role in still life images like this. The domino looks a little grey. You might try stronger lighting in front - otherwise just play around a bit.
Focus appears soft. Dominoes could've been arranged in a bit more imaginative or creative manner. Not enough variation. Image fails to grasp my attention.