Cool and original concept! Controlling both yourself and the enemy is definitely an interesting mechanic. The art was also pretty nice.
If you expand the game in the future, consider adding a reset button and tweaking the lives system if more levels are added, because losing at the last level and then having to go through all the previous levels just to try it again wouldn't feel very good.
Other than that, the game is really good and could be expanded with new levels in the future.