A nice little game. It took a while to figure out the rules. There is too little interaction between the game and the player. There is too little indication when you successfully created the path.
These can be repaired easily, or the publisher can simply add a description in the game, or in the author's comments. Overall i am not too bothered with them.
I would give it a 3 for the idea , 3 for implementation and 4 for the puzzle design.
Indeed the puzzles are not extremely complicated ... but i enjoined figuring them out. Personally i prefer these moderate difficulty games, than the ones that frustrate you for hours.
I guess it is a nice learning project for Unity 2d. Good job!