This game will be more fun when you add sound.

I am not really a fan of a puzzle game, but I hope the puzzle piece will be more snappy I guess, so not just the right part got snapped to the place that will make the puzzle neater.

And I dunno what should I do after finishing the game. maybe you should give choice to players to back to the main menu so they can select the next puzzle.

I found that some puzzle piece is stuck in another place so there is an empty place because the piece is stuck somewhere else.

Maybe you can also add a timer or kind of stopwatch maybe, that can be an indicator for the highest score or how fast the player solves the puzzle, it will add more sense of achievement I guess.

Great job :)