I just gave it a quick try and it's a great job for your first game! I like how you added the instruction screens and defined the controls you use. I wish more people started out took the time to make a complete game like this. It's extremely beneficial and speaks highly of you. The only suggestion I would make is that I would change the color of the line and dot to help indicate the current player. When the lines are drawn they can all be the same color, but it just would visually help remind people that it's the next players turn. You do change the text to indicate the current players turn, but another visual indicator would be nice.
Other than that, I have to see it's a very nicely put together game. Simple, easy to play and complete. Nicely done.