I love the idea presented for this game. It's simple and brings logical thinking to tackle a challenge. Most puzzle games with this simplicity go about it in 2D, so I like that you went with 3D for this. I do have some issues with the game, however.
The lack of a user interface to reset or to switch to a different level was a bit annoying. I felt like there was a bug where the wood wouldn't fill in the gaps despite it visually looking like it would, seemingly mostly because I missed an area. Having the wood fill in the gaps partially off the bat after you set it up to do so, and only stopping the wood when it hits the other wood would help communicate what the player needs to do. You could use this with your lose condition where you have a limited number of tries (which should also be displayed so the player knows).
Overall, again this game looks really good, especially for your first game. I hope you continue working on it more as it seems like it would be a great app for the google play store.