I thought the ambiance of the game was really relaxing, which was nice. I also ran into a lot of lag in the browser version after level 2, which caused some wacky physics glitches. The boats physically pushing the scale over is a hilarious fail condition.
I also noticed that because the cursor sets the (x,y,z) position of a block, I could just stack both sides full of blocks right away. Then I could grab one block to control the angle of the bridge by either lifting it up or pressing it into the bridge. I'm not sure if this is the intended way to play (essentially, putting your thumb on the scale!), but you could consider toggling the block physics off on click, then snapping their position to the scale if they overlap on release.