Cool little puzzle, some things I noticed:
There is no way to reset dominoes after they fell over. To slightly adjust them for example. You have to place all dominoes again.
(Maybe that's intended, but I felt like I was missing that)
And in one level when the wall goes down. I'm not sure if it was intended to be reached by deleting the domino that was holding the gate down, but that's how I managed to win after deleting the dominoes when I thought I had failed.
Basically, I finished the level only after deleting the domino instead of just after the dominoes finished falling