Your idea for combat was very interesting and something that I have not seen tried before. I think something that you could do to possibly improve the combat is increase the tolerance on how much of the line you have to cross in order for it to count as a pass. Also, centering the camera on the player when in the over world could have the potential to let the player see the fish and have more time to react to them before they accidentally run into them. Overall, great concept for a game and keep up the hard work!